Well, it depends. I think you mean "Université" by "college". The mistake is often made I think. "college" is "Université".You're 17, so I guess it's University you're talking about, isn't it?
Then what you mean by "I'm going to start college" is in French : "Je vais entrer à l'Université" I guess if anyone could concur, it would be better, but I really think that "entrer à l'Université" is okay.