I began developing breasts when I was about 8 and my 9 year old niece is already an A cup.  Neither of us have CAH.  Sometimes it is just a family history thing.  I can also say that I developed breasts long before I started getting my period (which happened around 12).  So, to make a long story short, I think can be normal but I would ask your daughters endo just to make sure.

Robin