I just introduced my 14-week old chickens to the coop (due to reasons beyond my control the coop was delayed in being constructed). I blocked access to the nesting boxes, and have a roosting bar (higher than the boxes), and food and water inside the coop (in non-spill feeders). I put them in the coop in the evening the first day and they got up on the roosting bar within an hour after that.
It was fun to watch them jostling for position on the roosting bar. I'll keep them inside the coop for at least 5 days before opening the pop door for them to go into the run. Hopefully, by then they will be habituated to the coop and the roosting bar and will automatically go there at sundown. That's MY plan, anyway - the chickens may not play along!
This is exactly what I did and it worked great.