Yeah!!! You just answered a nagging question for me and didn't even have to ask it.
my husband wants them out in the baby coop (yes we will have a separate area just for the babies) as soon as possible. I was thinking 4 weeks but as soon as those chicks feather out I'll set up the outdoor lamp for crazy weather spurts and go from there. 2 weeks before hatch. Working on big birds 8'x8'x6.5' tall Barn. Not coop barnand until we get the privacy fence up they will play in a large 10'x10' run next to the 5'x10' area for the babies. Yes we are using hardware cloth not chicken mesh. We will also line the entire yard with 6" deep wire and skirt it out 1' all around. My mamma hen dog will patrol the outer yard and sloped cover will let them out during weather but keep them dry.
If, by "outdoor lamp" you mean a heat lamp, I wouldn't recommend it. There have been far too many fires as a result of heat lamps in chicken coops to consider it a viable option. Besides, chickens are highly unlikely to gather together in the middle of the floor overnight (they will huddle up against a wall or under things), and so such a lamp would end up being near a wall...and there is your potential fire hazard again.
Trust me when I say, if they are fully feathered, they will be fine without an additional heat source. Move them from the brooder to the baby coop as they are ready, they don't all have to go at the same time.
Otherwise, your setup sounds great!
