Day 1 is appropriate really. They just become used to the artificial red heat lamps, nothing wrong with them but that become's their norm. They'll peep/cry for a few nights once it's taken away, but they'll soon adjust. Some people use a
brinsea ecoglow, or heating pad cave, etc as a brooder and turn the lights off at night from day one and the chicks learn day and night early on. I've used them all - first a red lamp before moving to a "mama heating pad" (which I liked at first, but wound up not so much), and ultimately invested in a
Brinsea ecoglow that I now use for my brooder heat.
Currently, I'm brooding with the
Brinsea but have the light on in the basement because I was brooding a few different batches (1 lamp, 1 heat pad, 1
Brinsea) because of hatch dates, size, etc so the light from the lamp stayed on. I moved the lamp chickens outside yesterday and they had no light last night and survived it at 4 weeks old. The batch of chicks left in the basement (2 weeks old) will get a dozen chicks added to them tomorrow in a divided brooder and I'll be using the
brinsea and the heat pad and the lights will go off at night on all of them to get them use to it.
I said all that to basically say this - turn the lights off if they don't need heat (once feathered, 4+ weeks usually), and they'll adjust well enough.
