Oooh oooh!!! I was going to start this very thread today.
I am 13 weeks and they are still sooooo heavy and sore. I have no recollection as to whether they were still sore at this point last time, so hopefully someone will be along soon with a better memory than me.
I'm 27+4 and mine are fine now - have been since about 16 weeks - my doctor in the USA said they'd be painful until I finished breast feeding, but I now think that's probably a worst case scenario! At least, I hope so...
MIne were agony-they are big too- until 18 weeks or so. Now absolutely fine and I am 35 weeks. I think it varies. get a good well fitting bra. I had to hold mine whenever I went downstairs!!! very elegant!