Depends upon how old they are & how far they can potentially roam. Another consideration is whether they come to you when called. That will help you teach them to come to roost at night. You may have to round them up for a while and put them away, or keep them cooped up for a few days to teach them that's "home".
I live in a surburban neighborhood with neighbors and an alley. Everything is fenced (until a chicken finds a hole, that is). We would let them out for the day when they were still in the brooder - about 4-5 weeks old. Once the coop was done & in place, one day we turned around and the 4 chickens were gone. They'd put themselves away for the night! Now it's a nightly thing around 7:30p. I'm surprised they go to bed so early, to be honest. It's typically light until 9 here.