I finally got smart and had husband build a GIANT brooder box with screen lids. My coop is great, for big birds. Not so much for babies. So they'll be in the house awhile. I chose the basement, since it stays a stable temp better than the rest of the house, no one lives down there, and there's a door close by to remove bedding without tracking it all through the house when I clean it.
Used to be they grew out of the brooder quickly, and had to go outside. With mine hatching... yesterday, they'll be outside ready as soon as it gets cold. So I've made winter friendly arrangements for them, in the brooder that will be big enough for 8 weeks, then dog crates, then as soon as it's warm, the big girl house outside.
I bought my hens before my coop was done... but I have a shed with a dog kennel attached to it that came with the house, so it wasn't bad keeping them there temporarily after I got a roof on the run.