They won't always take in chicks though even if they were broody i had tried with one at 3 weeks during the night and she was like nope, kept trying every so often, gave her eggs from her sisters and nope those weren't hers she wasn't going have any of that either, took putting one under her as it was hatching to finally break her after 4 months, it hatched she sat there with it for about 10 minutes then off she went and hasn't been broody since lolI mean eggs not chicks. I don't think she'll take in chicks until she is at the point her own chicks would be hatching. She might count days so well, so that's why I said two weeks. They would normally hatch in 3 weeks. This is my experience with introducing chicks to a broody, anyway. Be prepared to watch closely and if she starts pecking at them, then you will have to be mom and put them in a brooder. Eggs...she'll either sit or she won't. So much easier.
This was after broody busting failed, even tried the wired cage off the ground with ice packs under her