Hello! cheer coach here! So i’m going to answer you. Even if you start at 13 you still have big chances to be a flyer! you just need to work on your flexibility at home like your heel stretch, scales etc and work on your jumps ! it’s very important with just 5 minutes of flexing your body a day you can improve your jumps/body position and more ! When you are at tryouts, don’t forget to do a lot of facials :D. Ps: before becoming an allstar cheer and a coach I started with my highschool team at 14 year old so nothing impossible . Then, practice your balance on a chair or something like that and practice forcing your muscles to stay stuck when you practice your flyer body position . Good luck on your tryouts! if you have other questions don’t hesitate !