Have you already had orientation for your program?
At our orientation, we learned that they recommend that (1) we learn some medical terminology / medical abbreviations (suggesting a specific book). (2) We do some dosage calculation math (suggesting a specific book AND telling us that there will be a test the first day). (3) Read the first 12 chapters of the PE/Assessment text that we've been assigned.
In addition to that, I've started learning some common lab values (what makes up a CBC? What are the normal ranges? what's in a CMP? What are the normal ranges?) In some of my pre-reqs, they seemed to assume that we knew the normal ranges, so I'm not sure if I'm behind or ahead on this one! (I used the Saunders NCLEX study guide
, RNotes pocket guide and some free, user-created flashcards over at Quizlet.com to get me started on this. I know that the values can vary a bit from lab to lab and some instructors may want you to know a very specific "right" number, but I figure I'll at least have an anchor-point for next semester.)
Maybe check out the nursing section at your local Barnes & Noble just to get a feel for some of the supplemental books and pocket guides that are out there (but wait until the program starts or until you talk to some people ahead of you so you'll know which ones are worth buying vs. borrowing/using at the library/skimming at B&N while you have a coffee fueled study session in their cafe). At my B&N, the nursing section was a mess. Overall books didn't seem to be grouped by topic OR by author so I had to look around to find some of the series that I've heard might be useful. Some of the ones that I thought looked interesting were the Pearson (formerly Prentice Hall) Reviews & Rationales series and the Davis Success series. I also thought the Davis "Notes" pocket guide series looked potentially useful, but I'm waiting until school starts.
The one book that I did already buy (because it seems like everyone recommended it -- and I liked it compared to others that I saw at B&N) was the Saunders NCLEX study guide. If you do pop in to B&N, you might like to LOOK at Saunders Student Nurse Planner to see if it's something that would interest you. I wouldn't rave about it, but I've enjoyed looking through the used copy that was "gifted" from someone ahead of me.