Mannequin's sketchbook,

[Veneq]

Fantastic start to your sketchbook - love the studies. I can second what Craig said - age really doesn't matter in this industry outside of the fact that in general, the older you are the more responsibilities you have to take you away from practicing and pushing yourself as hard as you may want to or need to. I didn't start trying to truly learn how to draw until my mid 20's. There are pros who didn't push for this career until they were in their 30's or 40's.

Only critique I have are to keep an eye on your proportions. Anyway, keep up the good work.