Make ahead: The dough can be made and do its first rise in the refrigerator for 12 hours.
Oven variation: Arrange a rack in the lower third of the oven. Place a baking sheet on the rack and heat the oven to 450°F. When ready to bake, place the skillet with dough on the preheated baking sheet and immediately reduce the oven temperature to 425°F. Bake until the edges of the focaccia are dark-golden brown, 15 to 20 minutes.
Storage: Focaccia is best the day it is made, but can be stored, well-wrapped, at room temperature for up to one day. The crust will soften as it sits.