I don't think that my story is totally typical, but it worked pretty quickly for me. I was on the protocol for a long time (8 months the first time, 11 months the second) and I did bcp's instead of the prometrium, but the first time it was a stork drop situation, so I started pumping the day she was placed with us. I was able to stop supplementing when she was 2 weeks old and never had to supplement again. She was small (5lbs 12oz) which did help (she didn't need a ton of milk), but it did work for me. The second time we were matched and I started pumping about 10 days before the baby was due. I was making about 5-6 oz when she was born and I started nursing her when she came home from the hospital (at 2 days old). We supplemented with frozen breast milk. When she was 2 weeks old (and we were back at home - we adopted out of state) I stopped supplementing and ebf from that point on.
It is WAY harder than bf a bio child, but it is so worth it. Don't give up on it before you even start.
Jennifer