Yeah, what they said. Sometimes when I first open the door they are all on the ground within fifteen minutes. Well actually only once was it that fast. Sometimes it takes three days for the first one to build up the courage to try it outside. It’s funny watching them at the open door looking out but afraid to risk it.
What’s more normal (if anything can be considered normal) is that they look at it for a few hours, especially the braver ones, and eventually one or two hop outside for a bit then soon go back inside. But after a while they go out and stay longer and others slowly join them. Quite often that can be the next day. The end result, whether it is fifteen minutes or three days, they eventually go in and out as they wish.
Something else to prepare for mentally. Even if you have housed them in that coop for weeks and they think of it as a safe place, don’t be surprised if you find them at the foot of that ramp or even under it at night instead of going into the coop to sleep. Mine tend to do that a lot. Just pick them up and toss them in the coop if that happens. If you wait until it is really dark and don’t have much light out there it is pretty easy to pick them up. If it is pretty light it is more challenging. I’ve had some learn to go inside at night after doing that once. I’ve had a few that it took close to three weeks to learn. Each brood is unique, no consistency whatsoever.
You might be able to lure them in with treats just before dark and lock them in. If you train them to come to you for treats many things get easier.
Good luck!