Make sure you enjoy your summer. Don't try to pre-study. I did and it was a waste of time because when you're getting information thrown at you as fast as you do in vet school, you have to figure out new ways to retain the information anyway. I'm doing better academically in vet school than I did in most of undergrad because I had to figure out how to study efficiently.
This! I didn't study one bit the summer before vet school and I don't regret it at all. I was out of school for two years between undergrad and vet school, but it wasn't a huge adjustment for me being back in classes. Getting used to the volume of material is rough, but I think that's the case for everybody. If you feel the need to do something productive with your summer, work on getting the rest of your life under control -- develop a workout routine if you don't have one already, learn to cook/do meal-prep, clean out your closet and try to downsize some if you'll be moving for school, etc. Taking care of cooking/cleaning/exercise/other general adult things will become SO much harder once school starts. Put all of your bills that you can on auto-pay, I think LIS always recommends that and I agree.
I second the suggestions to make sure to take time for yourself, your hobbies, and hanging out with friends. If you have an SO (whether long-distance or living with you) don't forget to make time for them. Don't feel guilty about taking the occasional night off from studying, or going to bed at a reasonable hour the night before an exam rather than pulling an all-nighter. Your grades will seriously be better if you give your brain a break, get a good night's sleep, and take care of yourself. And like WZ said, don't feel guilty about making time to go shadow in the hospital, go to a club meeting/wet lab or go get hands-on experience somewhere. Those unique experiences will hopefully be what sticks with you 10 years from now, rather than random details from anatomy. I haven't done very well at going over to the hospital this semester, but I'm hoping to do that more next semester.
Here our schedule is lectures from 8 or 9 until noon, then an hour for lunch, and then afternoons are electives and labs. We get done at 4 or 5 most days, maybe earlier if it's a short lab. We don't have classes on Fridays, other than one elective that starts mid-semester and meets Friday afternoons, but the majority of our exams are on Friday mornings. The rest of Friday tends to be used for appointments, cleaning, sleeping and getting caught up on non-school stuff. Most of the time we just have one exam per week, so it's easy to focus on studying for the next upcoming test, but not really cram in the sense of waiting until the night before to start studying. Next semester's schedule is similar, but then second year switches things up (I think their tests are mostly on Wednesdays). This semester we've just had three core classes; gross anatomy, microanatomy and physiology. I had 8 classes total, but the rest were just one day a week each and all easy A's or pass/fail. Next semester we still have gross and physio, and add immunology and epidemiology. The only textbook we really needed this semester was the dissection guide, and apparently we just need the large animal dissection guide next semester too. I rented our physiology textbook from Amazon since that's been my most difficult class, but I never opened it because there just isn't time to sift through the book for the sections that are relevant to what we talked about in class.
I agree the best study methods will vary from person to person and class to class, so it's hard to figure out before you get there. I didn't have to change up my study methods
too much from undergrad -- I still type out study guides for each test basically rephrasing the lectures in my own words and focusing on the stuff I don't know. I started making Quizlet sets for each test, and just making them seems to really help even if I don't go back and review the flashcards. My class has a Quizlet group set up, so I can also look at other people's flashcards. I also study at school and with other people way more than I did in undergrad. In undergrad anatomy I could get away with just reviewing the material during class time, here you pretty much HAVE to go study in the lab on your own time in order to do well.
Oh, and don't freak out if you're used to making A's and are suddenly making B's and C's on exams. It happens to everyone in vet school, and seriously, C = DVM. You'll probably need a good GPA if you want to specialize, but that doesn't mean you have to make a 4.0 right off the bat. If you're legitimately failing, there are ways to get help (go to professors' office hours, get a tutor, switch up your study methods, etc.), but don't be that person that says "omg I failed that test!!!" when you made a B.
Anyway, sorry I kind of wrote a novel, but hopefully it's helpful!
this past semester we had a lot of free blocks in our schedule, 3+ hour lunch breaks, and Wednesdays where we ended pretty early. granted, next semester will be much, much busier and more intense. and it sure doesn't slow down after that. that said, I can't say that my fall semester experience is a guarantee for every first year class that is to come through in the future. I think I remember second years telling me that they had a substantial amount of free time as well, though not as much as we have had. 
