It may not be typical, but it is normal. I had visible growth and tenderness in the first week. This doesn't necessarily mean they'll be bigger, mind you; the speed at which they grow doesn't change the final size. (And I second the fact that it usually goes in spurts.) It does possibly change how much time you have to plan to come out, though.
I knew one girl in middle school who left for the summer flat-chested and came back with boobs. I used to wonder how that was possible. 😉