First of all, congrats on getting into Cornell. That's great!
I took a year off after college to apply for grad school and work for my dad. That wasn't the goal, that was the result of a late realization. If I had it to do over again, knowing what I'd want to do, I wouldn't have waited. Other than my desire for a break (which wore off late August), it became an exercise in patience, just waiting to actually get started in my current track.
For you, it sounds like you have a large set of other goals that expressly aren't academic, so it probably won't feel like waiting to you. You've already made the decision, it sounds like, so enjoy yourself and don't dread college one bit. I remember I had quite a bit of college anxiety. It went away once I actually got there and got started - my experience with it was very positive. High school is an obligation. College is a privilege, and it's a lot of fun.
VulcanRider's internship suggestion is worth considering. From my experience, only one of my friends actually graduated with what they thought they were interested in when they started college. Internships helped a lot of them out that way, realizing that their previous goals were unpleasant, boring, or unimportant in practice. Most of em are pretty happy with what they're doing now. The one who stuck with his goal (pre-medicine) had already had internship experience, and knew he was up for it. He just passed his board exams. Again, sounds like you've got plans, so internships can wait for summer breaks when you start next year.
As for VR's warning about forgetting stuff, I'd agree or disagree based on your interest. If your interest is math or chemistry/physics, I'd agree whole-heartedly. If it's something else just don't lose your writing skills - those are crucial in just about everything. Some disciplines give you a good refresher in their introductory courses, and others are such that nothing you can learn in highschool will be of any value. Social science isn't generally taught in high school, so intros to sociology or anthropology are true introductions.
Or, consider a statement made from a brilliant professor of mine: The whole point of college is to unlearn (at least re-examine) all the crap force-fed to you in your first 18 years
