Ducklings

Hi any advice greatly appreciated. I have 3 ducks, 1 female minature appleyard, and a breeding pair of white call ducks. The minature Appleyard, Jessica, has succesfully hatched 5 babys , 1 of her own cross, and 4 pure call ducks, At what age should I separate them from mum? At the moment they are penned up together, with the call ducks free ranging in the garden, but being penned up at night. At what age should I sell them, and  for how much ? I have purchased an incubator, and have 10 fertile call duck eggs in there. Any advice on how to manage these after hatching would be most welcome. Karen