How long do you have to preheat the oven when baking lemon squares?
A good rule of thumb is about 10 to 15 minutes. Most ovens will have a red light or beep that will let you know when the oven has been preheated. The red light will either go off or come on. It depends on the brand. If you have an oven that is fewer than 10 years old it may beep. Of course that depends on brand and model. If you have a stove and oven combination with the knobs behind the stove heating units the little red light will be by the clock and close to the light that lets you know the stove is on. If you have an older model you can purchase inexpensively an oven thermometer that you can hang from the racks. Or you can purchase a digital thermometer. See website below.
