When you first put the youngsters in the coop, keep them confined inside for a few days to allow them to become used to their new home. Then they should go inside at dusk all on their own, as they know where food, water and roosts are. They do not need light to find the roost, they will roost when the light starts fading on their own. It might be more disorienting to have sudden dark then natural gradually decreasing light. It is better for birds to have natural dark at night, just like it is for people, as it allows for better rest.
Often young birds will sleep on the floor or in nest boxes when young, but they will eventually make their way onto the roosts. Block off the nest boxes if necessary to exclude them until they are older.
Often young birds will sleep on the floor or in nest boxes when young, but they will eventually make their way onto the roosts. Block off the nest boxes if necessary to exclude them until they are older.