Yeah, I agree with pps. You parent the child you have, and barring any sort of reasons why they would have MORE challenges in learning social acumen, I see no reason to start gentle reminders as early as you want. It's basically just getting them used to the idea that certain settings have different rules and to be mindful of them. We have been asking dd to say please and thank you since about 18 mos, and shes two now and says it on her own about 10% of the time. I call that success!