Our 8-1/2 month old is quite mobile now so she's started to go after things she shouldn't. For example, our outlets are covered but she still wants to go play with the covers. So I started tryinh a firm No. I'm pretty sure by her reaction she understands, it at least makes her stop for a second or two. Then if she keeps going I say no and pick her up and move her.
When'd you start saying No?
When do you think your LO understood No?