ASAP Get them in there. Broody hormones are high at hatching, and begins to fall after than, often times they are GONE by week four. Broody hormones are what causes a mama to defend the chicks. Once the hormones disappear, hens forget they ever had chicks. And about that time is when new broody hen people start thinking about adding them back to the flock, and it is a disaster.
A lot depends on how you did it. If you separated the hen at the beginning of the setting, she is a totally strange bird to the flock. If they were or have been in sight of the flock the whole time, but separated, it is not quite a stranger, but it is not a go either.
A LOT depends on on your set up. Does it have hide outs, does it have places where a hen can strategically defend them such as a corner? A lot of people on here will show empty runs, where as, every bird in the run can see every other bird in the run 100% of the time - and that causes a lot of problems.
If you have clutter in there. Pallets, ladders, sawhorse, boxes, totes, mini walls, multiple feed stations set up so that, a bird eating at one sight cannot see a bird eating at another site, then this is what I would do ASAP:
- Let the layers out, mid morning. I would not lock them out, but I would chase them out a ways. Mine love getting out, but when they are out, one or two come back into the run, and leave at will, others come back in later and leave. Relaxed, that is what you want.
- I would put the broody hen in the run, with the chicks, watch what she does with them, a pallet up on blocks, but very close to the ground can be very helpful near her chosen spot. I would put feed on one edge, near her, so that the chicks can eat it, under the pallet, and she can defend it.
- Keep a close look out, but some birds will come back in, and that is good. She can manage against a few birds. One bird against 15, is considerably different than one bird against two or three.
- Watch the broody, she should puff up, big time, change her cluck, and establish her space for her and the chicks.
- Do put clean bedding in the coop, as in the late afternoon, much earlier than the layers will go in, she will go in and make a nest for her and the chicks. Clean out the whole floor, and let her pick where she wants. I have several times tried to encourage her, but she has NEVER liked what I thought was good. I quit trying. However, if it is directly under the roosts, I do and try set up a "roof" over her, sometimes better than others.
Soon after hatching, hormones are high, sooner is better.
Mrs K