My chicks stay in a brooder with heatlamp in the bsmt bathroom (unheated except for my oil fired portable) till they outgrow the space. How soon they outgrow it depends on how many there are. If I have 10, they outgrow it in a month, 15 in three weeks, 25 in two weeks usually.
After that, I have a nursery coop with heat lamps set up for them outside that works pretty well.
This next hatch, however, I may be in a position that I have to keep this next batch of over 20 in the bsmt brooder for a month, unless I can figure out something. I have some chicks in the nursery coop outside from five weeks to eight weeks old. By the end of January, all the extras except the couple I'm keeping will be gone to their new homes, but by then, my current hatch will be 4 weeks old and more than large enough to be out of the brooder. It's going to be a balancing act between brooder and nursery coop since I can't put 4-week-olds with 12-week-olds.