We have three 3-week olds and one 1-week-old chick. They've been going for progressively longer field trips to the backyard when we can be out there with them, and they LOVE it. I think the bigger ones are already totally over being in the brooder.
I've been thinking about moving them outside sooner than the normally prescribed 6 weeks even though I do not plan to run electricity to the coop - our day temps have been hovering around 80 and go no lower than 60 at night. From what I've read on this forum it seems that this is feasible.
Question is - what about the smaller chick? She definitely still is using the heat lamp at this point (when sleeping she chooses to be on the outskirts of it's light) but could she potentially go out in a couple weeks with the big girls? They do generally sleep all snuggled up, with the smallest one closest to the light and the others out in a line from there.