When did you go bra shopping after you stopped nursing/pumping? or when did your boobs stop changing shape?

My last pumping session was 2 1/2 weeks ago, and I'm confident that my boobs are fully empty now. Sadly, they don't come anywhere near filling up my nursing bras, but my pre-pregnancy bras don't fit well either. How long did you wait before you went bra shopping, if you needed to purchase new ones? I have time to go tomorrow, but am concerned that they may keep changing shape over the next few weeks....am I "safe"?