My chicks went to an insulated, venilated coop at about 2 1/2 weeks. With a 250 watt red light.
Today at 3 weeks and 5 days I let them out into the fenced in run.
Hesitant at first then out and exploring! What fun.....
I started them on smallest size grit about 5-6 days ago, sprinkling it on their food, once a day.
Feeling this would get them ready for the grass and bugs.
It was fun!