I only have 4 and I'm in CA, they were born in July. I had them in my bathtub (a secondary one) because I couldn't fit the brooder in the door of the house. I had a brooder plate and it was very nice. I only put bedding in a keyboard box under the brooder, because it was easier to clean. But they started flying around the bathroom at 10 days old (assuming they were 3 days old when I got them), and I couldn't contain them in the bathroom because the plug for the heat plate was outside the door (in the sink area). I already had the coop assembled outside, and it was warm, so I put them out there at one week old. They quickly showed me all the ways they could escape it, so I put them back inside until I fixed that (a few days), then put them out again. They never went under the brooder the whole time it was outside. It was in the closed area of the coop. I had it on a timer from 7:00 pm to 7:00 am and they avoided it like the plague. I was surprised that they didn't need it at that age, because they didn't get all their feathers until much later, they only had wing feathers. I put a flashlight in the coop (even now - 18 month old) at dusk to help them find their way to the roost, so they won't try sleeping outside in the tree in the run). I used to have to carry them to bed if I got home after dark, but they know I'm coming now, and just make their way in there when the light starts to fade. I try to remember to take it out once they are all up on the roost, but sometimes I forget. The point is, they know best, even if we think they don't. I would use your natural light and not worry about putting lights on and off during the night. They don't like when it's pitch dark, if they are not settled into their sleeping place.
