I was SO worried about mine roosting. They would rest and play on the roost I had in their coop but, they would not roost at night. They would go into the coop and sleep in a pile. I finally decided to put up my "permanent" roosts for them and a ladder. (before that I had one that was a little thin for them and only 1.5' off the floor) It took all of 3 days before all my chickens were roosting. That was a week ago at 11 weeks. They had been in their coop for a few weeks already and started putting themselves in at sundown the first day I let them out. I also keep feed in the coop, not the run so they are in and out all day and have a ramp (though they don't really need it) into the coop so that they feel as secure as possible. I had also not allow them into the run until I was sure they were "comfortable" in the coop...that took 1 night LOL. I never "forced" or even coaxed them outside but, I didn't coddle them inside either...they loved the greens in the run and I'd put treats in the run but, I would not make it "easy" on them and put treats/greens in the coop l...if they wanted it they had to get up the courage to go get it lol
My moral....they do roost on their own but, I think (in all my 12week experience) you need to make sure they have reason to do it and it is not "scary" for them....IE ramps, comfortable, inviting roosts. I like having food and water in the coop so that they go in and out all day and i don't have to worry about putting them up early or letting them out late since they have enough room, food and water.