I play roughly 5-6 hours each day. It took me like 4 days to get my main (a Warlock) to level 20. So I guess roughly 20-22 hours to reach level 20. Also grinding for armour with light was a bitch. I was stuck at level 21 for like 3 days. Stuck again at level 24 for over a week. Stuck on level 27 for 4-5 days. Now im 29 and will be stuck there until I acquire all the necessary raid gear. Oh well. In guess Instead of calling this game destiny. They should have called it searching or grinding. Lol