How long do I preheat my Flat Top? You will want to preheat the grill for approximately 20-25 minutes with the Flat Top in place. Related articles It is recommended that I brush food with oil before cooking, what if I can’t (eggs, pancakes, etc.)? How do I season my Flat Top? How do I clean my Flat Top? Why do I season my Flat Top? Can I cook frozen pizza on my Glazed Baking Stone?