I had a breast reduction when I was in my 30's after I had children and it's been amazing. I wish I had had it done sooner.
My teenage daughter is already a g cup, she is a size 12 and only 5'2. I think a reduction is the way to go, but would hate for her to go through it and them to regrow in pregnancy (hopefully many years away).
I would be intested to hear from anyone who had it done before they had children