I got my first ones at about 10 weeks mainly for comfort sake. I'm normally a 14C and went up to a 16C so I would have room in the back. I imagine they will fit for quite a bit longer unless I have some DRASTIC boob growth! Who knows! One was $40 - Loveable brand and I got a cheap $20 one from KMART which is quite good too. Just black and white to suit most clothes - they don't look too bad!