There used to be standardization of bra sizes. Projection off the chest wall, 1" = A 2" = B 3" = C 4" = D, this went out the window a while ago. In most places women may be three different bra sizes depending on the type, model, fabric, etc. In your case it is much too early to tell. As far as going by cc, 500 may be large for a little female, but relatively small for a large female. Best to get fitted when your plastic surgeon says it is time.
Web reference: http://www.jjrothmd.com/procedures/breast-augmentation