This is a very hard thing to do with children. Like I did it once and when i think about it now… Like I cannot make this up… I have no idea how I did. I just remember that he was big enough to understand what shame is. I am talking about my son Hugh. We uset to tell Hugh that he shoud be ashamed, he is a grown up now. He himself wanted to quit the napkins then. I think he was 3 years old. Yeah it took me a long while to decide to get him off the napkins. It was hard for me and for him too. I think that for about 6 months or even more he I used to put napkins at him during night time only. When he was asleep. Because he wasn’t able to detect whether he needed to pee or poo at night. So my advice would be around the time that the baby starts walking and talking… 2 years at least, earlier I don’t think is fit.