I pull them at around 5-6 weeks *I think*. When they are fast, with beady eyes, and are eating their own food (around 15g or so).
I never leave them in till they are feeder size. I just find I get fatalies of the pinks then, since they all huddle in one corner and bury the babes.
Same with separating them out to give females a risk. I leave established colonies alone and never separate them. They are fine with back to back breeding.
Ditto that, I wean once they got 'the look' like Bruce said, and if they get left in, the next litter of pinks are often smothered.