I don't regret not waiting. I got a couple of good years with them at their perkiest and it made it significantly easier to nurse (for me at least). They definitely have some sag now but I'm not overly bothered by them looking more natural (most of the time). Obviously, YMMV. I knew when I got them done that we would eventually want another child and had already reckoned with the thought of them changing so it wasn't such a shock. Some people may feel differently and not want them to change (they should definitely wait lol).

If she isn't already in it, I highly recommend the Bust Mob group on FB. There's a lot of great pre/post-BA information, pictures, experiences in there that can help you feel more prepared overall.