I followed your advice for the first time this spring with our first batch of this spring, in March. It was LIFE CHANGING! The biggest reason was, I had a group of 13, and it was JUST TOO MANY for my basement brooder.... My husband was NOT on board at first, and so I let him care for the babies in the basement, for about 3 days.... very shortly after, they went to the coop brooder! Those little boogers at 3 weeks wanted out, and did so just enough to make him crazy every time he went to change the water, food....etc.... LOL. I just sat in the kitchen and giggled every time I heard him cuss as he chased them around the basement. STILL makes me giggle thinking about it! With the group of 6 in May, we did keep them for a week in the basement, but... they went out ASAP...(he was of course the doubter). At 3 weeks, when I saw that one of the 6 was a cockerel, I cut the door, set up a ton of hiding spots.... let them free. Well, supervised visits in letting them free. By the end of their 5th week, the doors were open full time! Are they best buddies with the others?..... not yet... BUT, the cockerels are learning manners and the pullets are starting to integrate themselves with the other pullets. The older hens (3yr olds) have actually way more patience with the second round of babies!
I think EVERY person who has chickens should figure out a way to integrate their littles earlier! I REALLY think the reason we wait is, as a whole... we follow the WRONG advice! It is SO MUCH less stressful for ALL involved! The other reason is we look at these creatures as babies.... they are chickens, and need to act like chickens. We need to find a right and secure way to do this as it's the most natural way to establish new members! I just dont think I can go back to the basement brooder, ever.