Amana ACF4205A Owner's Manual page 17

In most cases, you should preheat the oven before baking. After the range control is
set, the oven temperature will begin to rise until the desired cooking temperature is
reached (approximately 8 to 10 minutes). When cooking temperature is reached
oven signal beeps. For delicate baking (such as puff pastries or souffles),
preheat approximately 15–20 minutes before placing food inside oven or wait
10 minutes after oven signal beeps before placing food in oven. The extra time
creates a more stable oven temperature.