Preheat

Refers to heating the oven to the desired temperature prior to adding food. This usually takes 10 to 15 minutes.

Recipes will remind you to turn on your oven before you are ready to bake something so that the oven has time to reach the desired temperature. Most ovens take between 8 and 10 minutes to reach 350°F. While it will not usually cause significant differences in the product if it is placed in the oven before it has come to the necessary temperature, it will affect baking time and browning.