I am currently in my 2nd semester of PT school. My advice for you, enjoy life while you can. haha
If you have the motivation, briefly (emphasis on BRIEFLY because the following really isn't necessary...only if you want to be slightly ahead...) skim through anatomy and bio mechanics...Origins, Insertions, Actions, Innervations of each muscle...you are going to have to know them and know them well. When does your program have your anatomy class scheduled? I know some programs do it right away in the first semester (like mine) and others wait until the second semester. If yours isn't until the second semester, then nevermind and just enjoy yourself...lol
Other than that, seriously...enjoy the free time you have. Its good that your working since that'll pass the time. What I am about to say varies from person to person and their circumstances and plans obviously, but if you can afford and dont plan on working when PT school starts, I would almost give yourself a month of pure freedom from all obligation before school starts. Go on vacations and do things that you have the time to do. Really take the time and treat yourself to some slacking off and enjoy your hobbies...Once when school starts, your there all week long. And try and land yourself a research job so you have a job that blends in with the PT program. I know my school has research positions that pay very nicely (pays my rent pretty much) and don't allow you to work over 6 hours a week.
But anyways, that's my two cents.
Don't drive yourself nuts, but really treat yourself if you can. See friends, family, etc...