Make sure to use an oven thermometer to truly know the temperature prior to starting the process. Because I use one, I know that my oven can be 25-50 degrees off of the digital setting for any temp above 400º. So I actually set my oven to 525º to ensure I hit that 500º mark.
Your oven typically will not be up to temp when it beeps. It may take 30-40 minutes to reach your intended temperature.