Take all of the AAMC exams if that's what you have access to. I'm not sure why two posters have said 9, because AAMC 11 wasn't available until just recently and now that 11 is out, 6 is gone. I thought it was 8 total.
If you can take between 10 and 12 full length CBTs spread over your last five weeks of preparing, that will be perfect. There are several threads on this if you search "practice CBTs" or something like that.