Well experience wise, the earlier the better. A lot of good horn and reed player I know started playing when they were in first year high school (probably 10-11 y/o) and they can jam with bands with no worries as they already know the fundamentals of scales, thier instruments and thier ears (if it's in tune or not). I was in the marching band since high school and in college and I play the trumpet back then (started 10 y/o) but my real forte is playing drums cause I started earlier (7 y/o) playing it. You can try playing sax at your age as long as you already know the basics and fundamentals of music such as: notes reading, atleast finished Solfeo (Note Reading Book), Know's how scales work and knows how to transpose notes from piano to sax and vice versa. If not then you'll have a long way to go. hehehe . I would also say that it also depend on what your goal is, is it just to play a basic song in sax for a single event or are you planing on joining an orchestra/ quartet/ band/ big band etc. or just for fun? Just my 2 cents