Yeah, I guess all babies are alittle different, but I'd say Charlotte learnt what "no" meant when she started repeating it back to me.I actually started to teach her, not so much NO, but "Be nice", and "Be Gentle", That started with a bunchof flowers i had on a low coffee table, when she was about 8-9 months old, and instead of having to put them up, i just thought i should teach her that yes she can look, and have a little touch, but just be gentle.... and i would sit there with her and show her how to be gentle.
I would take her hand and show her how, I figure, if its down and they can reach it, you may as well make life easier on yourself. And also on them as well because i am sure they get sick of hearing "no". Good Luck
~ Courtney