There's a difference between a hen using a nest for laying, even taking a long time to do it, and a hen going broody. Research the topic so you'll know when it happens. Sometimes they want to brood in the common nest boxes, sometimes they'll find their own private place.
I don't let my hens brood in the coop because they're often interrupted by other hens kicking them out & laying a new egg in the nest. Also, the hen can forget which nest was hers, and settle into another nest after her coffee breaks and let her developing chicks cool & die.
I use a 3-step process:
1. Wait to see if a hen will set brooding for at least 24 hours in the coop. Take out any eggs under her, leave fake eggs in their place.
2. The next night, take her & the nest box (I use flat-sided plastic horse buckets) to the separate cage I use for brooding. See if she'll stay on the nest there for another 24 hours.
3. The night after that, set the eggs I want to be hatched under the settled, committed broody hen. Go inside & mark the date on the calendar 20-21 days in the future.
I wish you & your hens success!
