It can take a few days, or longer if they are older chicks. You'll have an easier time using vet wrap - won't stick to her feathers. The human version is fine. It's that stretchy bandage wrap that sticks to itself:
Here's a video that shows how to apply it:
When I used the teacup method (a coffee cup or short drinking glass is fine), I used vet wrap to make a sling chair for my chick inside the cup with holes cut for the legs. But you could also use fabric or a sturdy paper towel
I put a bit of mashed paper towel in the bottom of the cup to give traction. Stretch the sling loosely over the cup; you can use a rubber band or some scotch tape around the outside of the cup to hold it in place. Put the chick into the sling, then stretch another piece of vet wrap over the chick's back, tightly, so that the chick is trapped between the layers of vet wrap and can't wiggle out. (But as it struggles to get out, it's strengthening its legs. Good!)
Then I made food and water cups. I used a couple of plastic measuring spoons with the handles cut short, but soda lids would probably be better. Tape them together, then tape them to the handle of the cup so the chick can reach them easily.
I only had the one newly hatched brooder with a heat lamp, so I placed the chick and cup inside a bigger container, then put that container in the brooder - just in the same range where the other chicks had arranged themselves comfortably between warm and cool zones. You could also place the cup inside your incubator.
By the next morning, the chick had wiggled its way out and was walking around just fine.
I would continue to dose with Poly-Vi-Sol (without iron) several times a day. They need the B-vitamins for neurological and leg issues. You could crush a B-complex tablet and dissolve it in water, instead.
