I studied off and on for about 3 weeks, FA and USMLEWorld, did just fine. It's hard to find a lot of time to study during your intern year if you're at a busy place, but just pick one book and stick with it. That plus a question bank is all you need. Familiarizing yourself with the CCS software can't be stressed enough. The cases are easy but getting used to the software is not something you will be able to adequately do with just the tutorial on test day and is how people fail that particular exam.