You are doing so great.
What do you think has been his favorite part of your blow job so far? Has he been showing his appreciation by moaning and humping your face? I think its time to let your throat feel what its like to get fucked.
Deep throat him 20 times in succession, reach the bottom and come back up all the way to the tip, and try not to gag. If you gag, you have failed him. Apologize to him while you rub his spit covered cock all over your face, ask his permission to try again and start over.