If you are in 8th grade, have been playing since you were in kindergarten, and are in the 4th suzuki book on violin, then I think that it is a hobby that you enjoy, but is unlikely to serve to catapult you into a T20 school. If you enjoy it (which it sounds as if you do), definitely you should continue. If there is an intensive strings program at a nearby conservatory program, to encourage development of young strings players, and you have the time and the motivation, sure. Philadelphia Youth Orchestra has such a program. Prysm Strings - PYO Music Institute
I would say that you are at the point and stage where you should do what you enjoy doing. You love to write, want to write novels? Great! You want to challenge yourself with some AP classes, in subjects you like, known to have a good teacher? Go for it! But don’t focus on any particular college yet, let alone on extremely competitive, professionally-focused programs. It’s too early. Be broad in your approach. At your age, just do what you love doing, and see which interests, activities, and subjects appeal to you the most, as you move along through high school. Get the best grades you can, put your all into the activities you love doing, and good things are sure to follow.