I would look online for skills videos (ie. NG tube insertion, bed bath, vitals, catheter insertion, etc.). Don't go too overboard on getting a jump start though, take this time to relax
Maybe get organized, buy your supplies, buy a good NCLEX book (ike Saunders or Kaplan), and get some R&R. You will be PLENTY busy when classes start. My best study advise is to do a lot of NCLEX questions on the subject you are doing in class at that time. Remember to not be hard on yourself, the program is challenging but just keep on studying and smiling.