No it's never too late! I didn't start gymnastics full time until I was 13—I just did it on and off before then—and at 13 i didnt have most skills but worked hard and competed within a few months
It's your choice if u want to do a big arm circle or a small one staying by your hips, for you I would recommend the smaller one because it's less of a transition from where your hands are running to where your hands would be ad circling I would start closer to the vault and do front handspring...