I put my chicks in a brooder in the coop straight out of the incubator, just a day or two old. As long as they have a place to go to that is warm enough in the coolest conditions and also have a place to go to that is cool enough in the warmest conditions they are really good at regulating their own heat.
A big challenge of brooding outside is the temperature swings. I've seen the temperature go from below freezing to in the 70's F (20's C) in 36 hours or less. I use a heat lamp but other things work well also. One area stays toasty and can even got too hot but the brooder is big enough and well enough ventilated that the far corner is cool enough. On the mornings there is ice in the far corner the area where the chicks are stays warm enough. My chicks move as they need to.