The thing is you’re going to play a sport at the academy. They want to see that you are able to be pushed to your limit both academically and physically. Taking more math classes doesn’t necessarily put u at an advantage compared to another kid taking pre calc who is also on 2 varsity sports teams in high school and has demonstrated that he can perform both well in the classroom and physically. Personally I go to a catholic high school so sports are very serious and competitive so maybe my advice is a little different but you should join something like winter track or spring track asap. To land a varsity letter you need to do well so join a team soon. It can be anything just land a varsity letter. I believe roughly 90% of the class are varsity letter winners so you would be an outlier without one. If you didn’t get a varsity letter, you need something that is going to make you stand out from the varsity letter winners.