I don't see why one would start with an NCLEX book. The questions make much more sense once you have learned the theory behind them and how to apply that knowledge in answering them. I think it would be hard to teach yourself the reason for rationales to the answers/questions.
I start nursing school
this fall, and I just asked a student ahead of me what the first lecture is over. I've been reading those chapters in my fundamentals book so I have a head start. Since every program varies in what they cover when, it is hard to give good advice that will apply directly to your program. If you are eager to begin, like most first time students would be, I would say just get your books and start studying the fundamentals one, since most likely that's what lectures will be based off.
There are plenty of students who go into programs without any prior experience, so reading ahead won't really give you a leg-up content wise. It'll just ease your workload once you first begin. As for studying, here is what I do/plan to do: Read the chapters pertaining to an upcoming lecture beforehand, then during lecture, take notes since the professor will add her own notes to the subject, and record the lecture. If I have time (that is, I will make time and do this:P), I will listen to the lecture again and read my notes as I go to make sure I didn't miss anything.
To prepare for a test on the subject matter, I will attempt to teach the concepts to another person (or myself, if no person is available). If I can't lecture to myself about the subject, then I do not know it well enough to be tested over it and will need to increase my knowledge in that area.
Besides lecture, I know a girl ahead of me who did well in clinicals/lecture but was having trouble with the Math for Nurses course. Part of it could have been the instructor, but she also didn't like math. If you feel this could be a problem for you, read up beforehand. Though I have heard it is easier than college algebra, so if you did that, I don't think it should be an issue.