You could work on your splits and other flexibility - like the pancake stretch, pike stretch, and do leg kicks. Also work on your strength - push-ups, sit-ups, pull-ups, toe rises, ...arms/abs/legs. You'll also gain a lot of strength and flexibility from the gymnastics moves themselves once you start gymnastics class.

Hi, I'm going to start gymnastics class soon and was wondering what things I can do to get ready and have a head start? Any certain types of excercises or flexibility? Thanks for the advice!