
We are very relaxed about this and have found over the years, that the milk is scattered better if leaving it for the bitch more or less to decide when rather than as some do, taking mums off the litters at a set time, abruptly. I like to have mine off their litters by around 6 weeks which gives me some more weeks before they go to their new homes, to make sure each puppy is doing well on their diet and of course, to give them time to play with each other which for me, is so important. It means they start to develop as well rounded individuals. And having mum away means when they go home (usually at 10 weeks for our litters) they only miss their familiar surroundings and litter-mates, not mum.
Early days most of their nourishment will still be coming from mum, but by 5 - 6 weeks no, mum isn't in with them at night and definitely NOT when they are eating - she only went in after they'd finished, to clean up and allow 'comfort nursing' - standing up. At that point, once she felt their sharp teeth, she'd want OUT - fast.