My bb's starting aching at around 9-10 weeks pregnant. My MIL took me to David Jones and had me properly fitted at 10 weeks and to my shock I had gone from a C cup to a D Cup and still in them now. Although they are very worn out and the bloody straps keep falling off my shoulders which is really annoying but I am waiting it out as I don't have long to go now and my cup size may increase when my milk comes in.

Oh by the way the lady who fitted me at DJ's said that if you don't get your bra's fitted properly especially when your pregnant it could end up damaging your milk ducts and make it hard to breast feed. Considering it doesn't cost anything extra for a fitting I think its better to be safe than sorry.