I've got a variety of ages of chicks, how old do they need to be before you switch to a layer feed? And would it be ok to keep feeding the older chicks the chick starter until they are all ready to have layer pellets? My oldest is about eight weeks with my youngest around two weeks. My thought was to feed chick starter until they were all able to be on the same food. Would this work, and at what age should they make the switch to layer?