What I do is wait for 24 hours after the first one hatches (because when the eggs are all set at the same time, usually all the eggs that are going to hatch will do so in that time), then move hen, chicks and any unhatched eggs to a nest on the floor. I never move a nest when the eggs are still in the process of hatching because I don’t want to bother the broody. The chicks stay pretty close to mama the first day or so anyway, and it won’t hurt them to wait a day or so for food and water.
In your case, it might be OK to move hen, chicks and eggs to the floor before then. There is a chance you may not get any chicks, or that the ones who hatch have developed poorly and will be unhealthy. When a hen has a large clutch, she can’t cover them all properly so some may never develop, some may develop with deformities, and some may develop without any problems. You just never know.