Do you already have eggs to put under her? If so, I'd go ahead and put them in front of her and let her pull them in. I'm guessing she could sit on about 8 eggs and cover them all.
I would mark those with a small X on each end with a pencil so you will know if another hen lays an egg in her nest, and you can remove it. Give her the eggs all at once; do not give her one every day nor let her sit on new eggs after she's started, or you'll have an issue when they hatch. When that happens, the last ones put/laid will most likely get abandoned as she'll have chicks to take care of.
It'll take 21 days. Once hatched, she'll bring them to the food/water. If you have other chickens, that's fine, she'll keep them away from her babies, but they can all share the same feeder if you either put chick crumbles in their feeder or switch them all to an all-flock. All flock is for chicks and adults. The hens would need oyster shell in a separate dish as that's lower calcium. If you do this, make sure the chicks can't get to the oyster shell.
Happy hatching!