I have silkies 2 Roo's 2 hens in the same coop as my Lavender Orpington Roo's and 2 lavender Orpington hens and about 14 buff hens. I want to start collecting eggs to hatch. I don't want a mix of silkies/Orpington chicks. How soon do I need to separate so I don't hatch out mixes?