Before I start, I will make it clear that I have even less experience with med school than you do.
First aid is a thick book with a lot of information. While you might not be able to memorize it in winter break, you could familiarize yourself with the book. One way you could do this is by making the skeleton of a data structure for your brain. What I mean by this is you could find one piece of information on each page that you recognize and then associate that page with that piece of information (i. e. the page that had to do with maternal disomy causing 25% of Parader-Willi). With that skeleton you could incorporate the method of loci into your studying during the dedicated study period as a form of last minute cramming (after all, isn't that what the dedicated study period is all about?).
I am curious to see what other people think though...