I have never had problems with them going to the coop at night, but we ALWAYS keep them in the coop for 3-4 days. The 1st chickens we ever got we kept in for 1 week. If you don't want to keep them in the coop you can put a fence (that they can't fly over) around the coop so they can get outside, but choose to roost in the coop cause that is the only option. After a week of that, they will go in the coop at night as long as there are suitable roosts in the coop.