C.P.
Your baby is the same age as mine! Sometimes he waves his hands at my face (trying to slap, but can't quite do it). I think that he's so young to listen. I've heard that babies this age understand "no", but don't always listen to it because of their age. I think you are doing the right thing, and the older he gets the better he will LISTEN to your "no's" Good Luck!!
C.