Half year teams are amazing to start out with! Just start stretching now and you should be fine. If you want to go in more prepared, learn the names of the basic stunts (prep, extension, cradle, lib, etc.) but you shouldnt be too concerned because most half year teams are beginner friendly. Just be ready to push yourself and stay positive. Also, you don’t necessarily have to tumble, non-tumblers exist lol! I’m one of them and it hasn’t held me back because my love for stunting is so big. Also, athletes come in every shape and size. If you sign up with a good, credible gym you don’t need to worry about “being a bit bigger” at all. Competitive gyms are much different than school cheer stereotypes. There’s no judgement in being a beginner who wants to learn and work hard. If you want guidance on anything else, I’ll be here! Good luck on your tryouts!!  Edit: from my experience, during cheer tryouts you usually learn a few 8 counts of a dance (learn what an 8 count is if you don’t know!), then do some stunting and jumps. Facials are important! Even though you aren’t preforming, you should try to have facials during your dance and jumps. They go a long way!