Takes a bit less than forever to preheat. The chime that signals that oven is ready sounds at 10-15 degrees below the pre-set level. After another 10-15 minutes it reaches and holds the pre-set temp.
The oven is amazing! It cooks very well and even especially the convection. We love using the WiFi to preheat. It has a built-in thermometer which reads perfect. Great feature!