Minwer Badwan and Rawhi Badwan appeal their convictions under 26 U.S.C. § 7206(1) for filing false federal income tax returns. They raise three issues on appeal: the denial of their motions for a continuance of the trial date, the denial of their untimely motion to suppress evidence, and the sufficiency of the evidence to prove all elements of a violation of 26 U.S.C. § 7206(1). We disagree with their contentions on each of these points and affirm.
I.
The appropriate standard and perspective for review of a denial of a motion for a continuance is found in Ungar v. Sarafite, 376 U.S. 575, 84 S.Ct. 841, 11 L.Ed.2d 921 (1976):
The matter of continuance is traditionally within the discretion of the trial judge, and it is not every denial of a request for more time that violates due process even if the party fails to offer evidence or is compelled to defend without counsel. Contrariwise, a myopic insistence upon expeditiousness in the face *1230of a justifiable request for delay can render the right to defend with counsel an empty formality. There are no mechanical tests for deciding when a denial of a continuance is so arbitrary as to violate due process. The answer must be found in the circumstances present in every case, particularly in the reasons presented to the trial judge at the time the request is denied.
Id. at 589, 84 S.Ct. at 849 (citations omitted) (emphasis supplied).
The denial of the Badwans’ motions for a continuance is the most troublesome issue presented by this case. Viewed from the perspective of the district court at the time it denied the motions, however, we cannot say that the district court abused its discretion.
A.
Minwer and Rawhi Badwan are brothers and were the sole partners in Virginia International Trading Company. (“VITC”). On March 5, 1979, a federal grand jury sitting in Alexandria, Virginia returned a five count indictment against Minwer Bad-wan and a four count indictment against Rawhi Badwan. Each was charged with filing false individual tax returns for the years 1972, 1973 and 1974. In addition, Minwer Badwan was charged with two counts and Rawhi Badwan with one count for filing false partnership tax returns for those same years.
On March 12, 1979, the Badwans appeared with retained counsel before the district court for arraignment. They pleaded not guilty and demanded a jury trial. The district court set the case for trial on April 3, 1979. All pretrial motions were to be submitted by March 21 and heard on March 23. With full opportunity to do so, defense counsel raised no objections to these dates. At oral argument in this court counsel explained that he did not object because he had not yet had a chance to review the evidence in the case. In addition, he said, he knew that the district court was not favorably disposed to grant motions for continuance.
On March 20, counsel filed a motion for an extension of time within which to file pre-trial motions and for a continuance of the trial date. In the motion, counsel represented that he had not been retained until March 9, so he had had no chance to investigate or research the case before indictment. On March 14 he had first met with an Assistant United States Attorney to begin pre-trial discovery. At that meeting counsel was presented “eight volumes of trial exhibits covering hundreds if not thousands of pages.” On March 16, the government attorney had called defense counsel to invite him to meet with the I.R.S. agent in charge of the investigation. A meeting had been arranged for March 20. On March 17, counsel had met with the Badwans and decided that a defense investigation would be necessary. The investigation would include the hiring of an accounting firm to review the available materials.
The motion concluded:
In light of the complexity of the case (e. g., the number of Government exhibits and the fact that the indictment covers nine different tax returns over a period of three years) counsel is compelled to request the additional time within which to file motions and a continuance of the trial date from April 3 to a date in late April or early May.
The district court denied the motion.
On the morning of the trial, counsel asked at the outset of the proceedings for permission to approach the bench. This exchange occurred:
COUNSEL: For the sake of the record, we, of course, are not ready for trial. And I have this morning handed your clerk a motion, a written motion, for a continuance or, in the alternative, to dismiss the indictment on the grounds of the defense being forced into a summary trial in this matter.
I also filed today a motion for suppression of evidence.
THE COURT: Why wasn’t that filed before?
*1231COUNSEL: For the simple reason, Your Honor, we just over the weekend decided that that had enough merit so that it should be filed. I have articulated in my written motion for a continuance, at least briefly, some of the problems we have been having.
THE COURT: At arraignment there was a time given within which to file motions and a time set for those motions. No motion was filed within that time. And I am unwilling to hear any motion to suppress evidence on the morning of trial with a jury sitting here waiting, and I am unwilling to continue the matter.
For those reasons, the motion will be denied.
B.
The defendants relied almost exclusively in their motions for continuance on the asserted complexity of the evidence in the case. The complexity of a case is undoubtedly one of the circumstances to be considered in deciding whether to grant or deny a motion for continuance. We are not prepared to say, however, that the district judge acted arbitrarily in concluding on the facts presented to him that three weeks was an adequate time in which to prepare a defense in this case.
Of the nine tax returns on which the prosecutions were based, six were the individual returns of the Badwans. Those returns merely reflected an equal division of the partnership profits of VITC. As to the partnership returns, the district court may simply have concluded that the amounts involved suggested some limits to the complexity of the case. The indictments charged that the correct amount of partnership profits was $29,109.13 for 1973, $20,-994.48 for 1974 and $24,586.71 for 1975. The Badwans reported partnership profits for those years of $4,096, $6,300 and $13,-568.
There are other factors here that support the district court’s denial of the motions as at least not arbitrary. First, there is defense counsel’s silence at arraignment when the trial date was set. Counsel may not have known then of the particular problems he would face in this case, but he must be assumed to have known of the potential complexity of any tax fraud prosecution. He must also be assumed to have known of the likely difficulty of hiring an accountant during the month of March to review the government’s computations and analysis. A district judge, aware of the same facts of life, and entitled, as he must be, to assume counsel’s zeal in protecting his client’s interest, must ordinarily then be entitled to draw the obvious inference from counsel’s silence in the face of clear opportunity to signal concern. From these practical considerations has emerged the general principle that an attorney having a substantial claim for a continuance should move for the continuance as early as possible. United States v. Uptain, 531 F.2d 1281, 1290-91 (5th Cir. 1976). The later the motion is made the more disruptive will be any continuance granted, and the more likely may it reasonably appear to the judge that the motion is made for dilatory purposes. All this must be taken into account in assessing claims of arbitrariness in denying a continuance, and here it militates against defendants’ claim.
Second, the defendants have never shown in any concrete way how they were prejudiced by the denial of the continuance. They have argued to us that further investigation “could have led to many innocent explanations for the alleged understatements.” We must be reluctant to find arbitrariness in the exercise of trial court discretion based upon no more than post-hoc assertions by counsel that given more time something might have turned up. See, e. g., United States v. Uptain, 531 F.2d 1281 (5th Cir. 1976); United States v. Schwanke, 598 F.2d 575, 579-80 (10th Cir. 1979). This case is not, for example, like Shirley v. North Carolina, 528 F.2d 819 (4th Cir. 1975), where it was demonstrated that the testimony of an unavoidably absent witness would, if believed, have led to the defendant’s acquittal.
*1232We do not believe that the denial of a continuance here so clearly violated fundamental fairness or deprived the Badwans of the effective assistance of counsel as to compel a conclusion that it constituted an abuse of discretion.
II
The defendants also contend that the district court abused its discretion in denying, without a hearing, their motion to suppress evidence made on the morning of trial. The motion was based on asserted violations of Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966) in interviews held by an I.R.S. agent with the Badwans. The defendants assert that a hearing on voluntariness was required by Jackson v. Denno, 378 U.S. 368, 84 S.Ct. 1774, 12 L.Ed.2d 908 (1964).
Under Rule 12(b)(3) and (f) of the Federal Rules of Criminal Procedure, the failure to raise these claims before trial constituted a waiver. The defendants argue that the district court should have granted them relief from the waiver, as Rule 12(f) allows; that the early trial date made it impossible adequately to have researched and prepared the suppression motion before trial. None of the considerations that made the issue of the denial of continuance at least an arguable one are present here. The complexity of the other evidence in the case should not have affected defense counsel’s ability to challenge the voluntariness of statements by his clients.
We believe that the nine days from arraignment to the time for submission of pre-trial motions was sufficient for. preparation of the motion for suppression.
III
The defendants’ last contention is that the statute only applies to one who “willfully makes and subscribes” a false tax return. 26 U.S.C. § 7206(1). They argue that the evidence clearly showed that they did not “make” the return, but rather that the returns were prepared by an accountant hired by them. The evidence did clearly show, however, that the accountant who prepared the returns did so solely on the basis of information provided to him by the Badwans, and that the Badwans then signed and filed the returns. This satisfies the statute.
Having found no error on any of the points raised, we affirm the convictions.
AFFIRMED.