It's 110% up to you. How long before you leave? Obviously you don't want to throw them in with the big hens the same day you're leaving, never can tell how they will all handle each other. I would never give a chicken younger than 18wks layer feed but also, just because it's been done in the past does not mean that it can't actually cause problems for other chicks or even cause problems for the chickens when they are older (shorter life span)
Where are these younger chicks held? If they are in a coop or at least a big brooder then I'd buy them bigger containers. How will the big hens be getting their food/water?
Where are these younger chicks held? If they are in a coop or at least a big brooder then I'd buy them bigger containers. How will the big hens be getting their food/water?