If you are going lights off for the first time be prepared for them panicking. Don't drastically just shut lights off and leave them in darkness...try to let them experience dusk if you can. They will panic and be scared for the first few times but it's better for this to happen while they are still in a familiar environment. When you move to coop try to do it in morning so they have all day to explore and get comfortable before nightfall. I have learned from my own mistakes 
