CK is definitely not as bad as Step 1, but you still need to review. Anywhere from 1-3 weeks is a good amount of time for preparation. The key to this exam is QUESTIONS! I found USMLE World extremely helpful. It costs $90 for 30 days and has almost 2100 questions. The questions are much more difficult than what you will encounter on the actual exam. Practice scores ranging from 50% + correlate with decent scores on the exam. Once you get to the real exam, the questions seem even easier. A quick review of Crush the Boards, etc. is also helpful to brush up on info. Don't forget that Step 2 is an extra block long, with 8 blocks of 46 questions. Endurance is important!
CS is not difficult, especially if you have had a lot of clinical experience. I would suggest breezing through First Aid a couple of days ahead of time, just so you know what to expect yourself, as well as what the expectations of you are. The exam is very methodical, so talk to someone who has already taken it if possible. Sign up early to get a seat in Chicago, but otherwise, don't stress too much over this one.
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Alpha Omega Alpha
http://www2.uic.edu/stud_orgs/hon/aoa/