The unit will automatically begin preheating after the desired set cook level or time/temperature is selected. It will take approximately 10 minutes for the unit to preheat when using the Grill function and approximately 3 minutes when using all other functions. "ADD FOOD" will display when preaheating is complete. You can open the lid and add your food. Although preheating is recommended, you can skip preheat by pressing the preheat button. "ADD FOOD" will display, then you can open the lid and add your food.