My daughter who is almost 2 now had a tongue tie, and we found out about it at her 1 year old dentist appointment. We had her's fixed at 15 months. It was very traumatic for her, they put her on a papoose board, and she freaked out. It took my husband and a nurse to hold her down while the dentist clipped it, and the procedure itself took around 30 minutes to do because she was wiggling and screaming so much.
It took a couple of days to not bother her, and she dealt with some drooling for about a month afterwards, and also dealing with changing the way that she ate. She still has issues with talking, and even though our doctor is not concerned about it, we are.
I think, knowing what we know now, we would have done a few things differently had we known. We would have done it as soon as possible, and not waited until she was older, it was traumatic for her, because she was old enough to know that she did not like it, but not old enough to understand what they were doing. (She was completely numb, but there was a lot of equipment in her mouth, my husband is clausterphobic and said that is his worst nightmare.) And secondly I would have had her knocked out for it, so that she wouldn't have known what happened instead of the papoose board and numbing. Bottom line, I do not regret having it done, just how we had it done.
My best to you and your son, I hope this helps!