From USMLE.org Website
When applying for USMLE Steps 1, 2 CK, and 3 or scheduling test dates, please keep the following in mind:
Your Scheduling Permit includes specific information for contacting Prometric to schedule your test date(s) at the test center of your choice.
- You must have your Scheduling Permit before you contact Prometric to schedule a testing appointment. Appointments are assigned on a "first-come, first-served" basis; therefore, you should contact Prometric to schedule as soon as possible after you receive your Scheduling Permit.
- You may take the test on any day that it is offered during your assigned eligibility period, provided that there is space at the Prometric Test Center you choose.
- Prometric Test Centers are closed on major local holidays.
- USMLE Steps 1, 2 CK, and 3 are not available during the first two weeks of January.
- The busiest testing times in the Prometric testing network in the United States and Canada are May through July and November through December.
- Some, but not all, Prometric Test Centers are open on weekend days. When you schedule your Step 3 test dates, the two days on which you take the test must be consecutive, unless the center is closed on the day that follows your first day of testing. In that event, Prometric will assign you to the next day the center is open for your second day of testing. In all other cases, you must take Step 3 on two consecutive days at the same test center.