Different situation though. You're a guy and guys tend to pick up tumbling faster than girls. It's not always the case but almost all the guy cheerleaders I know got their tumbling quite quick.
Lily- tumbling it really depends. I struggled with a handspring for 2 years and then when I switched gyms I went from barely a standing handspring to working a running layout in 9 months. That being said I took many tumbling classes and privates and conditioned like crazy to get those skills.
As for flying that is not easy. I had to stretch every single day to get a straight leg scorp (needle) and learning things like fulls and such wasn't easy. But when I was learning to be a flyer we didn't need to have all these skills you need now. Cheer has progressed a LOT since I started. Being a flyer you are constantly learning new skills because stunting changes a lot whether it be how you get to the top or new stunts. I've based as well and that's just as important. A flyer can't get in the air without a base or backspot :)
I would aim to try and make any team and then work on skills and to progress from there.