When first start to let mine out I'd wait until about 30 minutes before they would normally go to roost. They stick pretty close to the coop as they know it's almost bedtime. After a few days I let them out a couple hours before roost time. A few days of them showing they'll go back to the coop when it's bedtime and I feel confident that they can free range.
Teaching them to come when called is good. I'm a snowbird so my girls used to spend the winter next door with the neighbor. When I got home for the summer I cleaned the coop. Saw the neighbor had mine and his girls all out free ranging. I called "here, chicky, chicky" as I'd done since they were babies. All 6 of my girls came running across the field to come home. They still remembered after 6 months of living next door.