Well I do tend to keep the chicks separately as well, either alone with their broody, or entirely separate if I have hatched in an incy. This is an attempt to keep them off ground occupied by adults as I have had cocci in the past, a very nasty disease, and I have enough space that I can provide new fresh ground for chicks.
In terms of the cocks and pullets, I keep large, slow maturing breeds (orps and a particular strain of red sussex), so I don't have many problems with the cocks bothering their siblings. When they start crowing and/or being annoying, then I start to separate them - either into the pot or rehoming or resale. I would say this is around 16 weeks at the earliest, right up to 26 weeks, but I know I am lucky.