Not sure how old a rooster has to be, but I'm sure someone here will answer.
I would buy an incubator. Until you have an idea of just how they work. From what I hear, once you get one incubator, one is never enough LOL. You could built a second one once you get the hang of the store bought one. You can find them at farm stores for about $50. Mine's a hovabator. Little Giants are about the same, i think.
Do you have your big and little chickens in the same pen?
I would buy an incubator. Until you have an idea of just how they work. From what I hear, once you get one incubator, one is never enough LOL. You could built a second one once you get the hang of the store bought one. You can find them at farm stores for about $50. Mine's a hovabator. Little Giants are about the same, i think.
Do you have your big and little chickens in the same pen?