Usually, you want your broody to have been sitting for longer than s few days since it takes 3weeks to hatch an egg, I’ve seen other BYCers recommend them to be sitting for a couple weeks.
Since you have chicks, you could try now or hold back for a few days and try then. The biggest risk is that she doesnt accept them and kills them.
We bought 5-day old chicks at a hatchery (from the bargain bin) to give to a broody. She was young, only 7 months old. She had been broody for approx 3weeks. We gave her the 5-day old chicks at night (in the dark), and she accepted them. This has been our only broody experience, so good luck with your broody.