They’ll be fine. I don’t know the winter temperatures in Florida, but It can’t be that cold. The chicks will be fully feathered by then and fully able to handle cooler temps.Is the weather okay to hatch chicks in Autumn in Florida? And do you have a good coop with windows to let the sun in?
If not , I wouldn’t let my hen stay on the nest and break her broodiness.
But if you have a great setup and good weather in winter I suppose it’s okay.