Jumping in to add my two cents. ;-)
Although you really HAVE to see CKs brooder and broody box setups. I think I have it bookmarked. Yes, I do....
Broody box
I use a 6x2 brooder for up to 45 birds. that's 4 birds in each foot at maximum capacity. I usually only pack this full with all meat birds/broilers. If they're meat birds, I can do 10 days. heritage birds can be in here at that capacity for 3-4 days, but then they're all over each other. I prefer 15-20 heritage birds and they can then stay for 2-3 weeks.
I try and get them on the ground within a week, 2 at the most. I usually go to where every bird has at least 1 foot of space, up to to 3. (The more space you give them in an actual brooder, the less they eat... I don't like to really allow them ALL the space until 3 weeks)
I keep them in a pen on the ground within or next to the adult flock, and start allowing them to integrate in the daytime only at 4 weeks old for broilers or larger heritage breeds, and I do 6 weeks for heritage birds. If I miss those timelines, I have issues with bullying because the babies are starting to get too big and close in size to the bigger birds. I do not allow the birds to cohabit space at night because I find that the last feedings and early morning feedings can get pushy. Plus, there's so much more room in the daytime outdoors for littles to get away. Without walls, I have never had a little pecked to injury... it's when they are within walls that the problems occur for me. . . .
Integration can be REALLY easy if you manage the flock. Some people don't want to do this, because it may mean getting rid of some favorites.... but.... I rehome ANY bird that is mean to chicks during integration. I haven't had to rehome an adult bird in over a year now.
