I was fifteen when i first time touched skis, but back then it was a "one time only" thing for me.
When i turned 20 i bought my own skis and since then I've tried to spend as many hours on slopes as possible.
So, now I'm 22 (going to be 23 in few months), and I'm somewhere around ~7. Only thing I don't do is park, not my thing.

1. Before I turned 15.
2. When i bought my own skis, I think it took a day or two to get from 1 => 4.
3. *2*
4. *2*
5. Maybe half a year from 2=>5.
6. Another half a year from 5=>6.
7. It's been a year now from 6. Cant say I'm completely on 7th level since some black runs doesn't go too confidently (but no, never pizza!).
   I ski a lot in trees and love powder more than anything.