I wean bucks/wethers at 3 months of age, and doelings at 4 months of age. Replacement doelings are housed/penned separately from the main herd from the day they are weaned until their kids are weaned at roughly 21-28 months of age. At that point they usually join the main herd. Although my mothers and daughters buddy up again, I've never had a daughter go back to nursing her mother.
In my experience, it takes 3 to 4 weeks for the doe to dry up. I wean the bucklings first. I put them in the pen with the buck. The doelings have to go in a barn stall. When I turned them out they tried to nurse, but the does let them know in no uncertain terms that they weren't going to put up with it.