It took my latest batch of chicks exactly one night in the coop to realize they preferred sleeping on the roosts rather than balled up on the floor, because if they jump up on the roost, they can see out the window. They also had roosts in the brooder to practice on. I think it feels natural for...
In addition to blocking off the nest box access and making roosts higher than the nest boxes, I went an extra step and picked mine up off the floor and stuck them on the roost bars at night. At least to give them the idea. A ramp helps if the roosts are extra high up.