I've just finished bfing ds2 and want to go and buy some new bras. I will get professionally fitted as I'm largish and get a bad back if I'm not in the correct size.

So, how long should I wait before my bbs setlle into their shape? Will they stay as they are now, or change over the next couple of months? I don't want to splurge on new bras now only to find they don't fit properly 2 months down the track.