I suggest the following:
-Find a local tutor to help you with spelling, grammar and any other academic deficiencies you may have.
-Either buy or make your own PC flashcards and study them now. They'll come in handy, trust me.
-Prepare your body for PT now. Running (work up to 2 miles minium) and calisthenics (push-ups, sit-ups, and pull-ups) are a must.
-As someone mentioned earlier, learn how to shine boots. Make sure the boots you're going to use are broken in prior to your start date.