How painful is Tommy John surgery and the recovery period?

Im 19 and have a complete tear of my UCL, the ligament reconstructed in Tommy John surgery. I go to the doctor next week and Im hoping to get the surgery as soon as possible. I was wondering what Im going to be looking at as far as pain from the surgery and recovery, how long my arm is going to be immobilized for, and if there is a preferred place I should have the graft tendon harvested from? Any tips would be helpful.