Agree with the earlier posts. Realize that everything will happen sooner for you that your non MT friends. You will feel “out of sync” with your friends, starting sooner, deciding later. But all MTs go through that (music in general does, my S experienced the same for trumpet performance this year).
Start checking out schools now. They don’t have to be your actual MT schools, but try to include some if possible. Try to figure out types of schools you like - large v. small, city v. rural, public v. private, etc. We went on a lot of college tours during spring break junior year.
Also, explain this to your parents and have them visit this site. What they go through will also be different than non-music parents experience. Help them to understand what you need, because you will need their help.