Jamieson, Fausset and Brown on Acts 24:11

11. thou mayest understand--canst easily learn.

that there are yet but twelve days since I went up to Jerusalem--namely, 1. The day of his arrival in Jerusalem (Ac 21:15-17); 2. The interview with James (Ac 21:18-26); 3. The assumption of the vow (Ac 21:26); 4, 5, 6. Continuance of the vow, interrupted by the arrest (Ac 21:27, &c.); 7. Arrest of Paul (Ac 21:27); 8. Paul before the Sanhedrim (Ac 22:30; 23:1-10); 9. Conspiracy of the Jews and defeat of it (Ac 23:12-24), and despatch of Paul from Jerusalem on the evening of the same day (Ac 23:23, 31); 10, 11, 12, 13. The remaining period referred to (Ac 24:1) [Meyer]. This short period is mentioned to show how unlikely it was that he should have had time to do what was charged against him.

for to worship--a very different purpose from that imputed to him.