Looks nice, should be close to pizza time.
In an oven a little smaller (GGF micro) with the same 2100W heating element, the baking time is around 45 seconds.
One thing you may want to watch out for is whether the sensor for the thermostat is in a good location. If it is too close to the element, it turn off the oven before it gets to the set temp.
Don't worry, the heating elements won't turn off until I push the On/ Off rocker switchs.
Since there are going to be hotspots and colder area's relative to the heatsource the temperature that hits the thermostat will not be equal to the temperature that hits the deck, unless the thermostat is build into the deck which is virtually impossible on a low budget. Calibration will probably be the most difficult aspect of this build and which will require lots of patience to do it right.
There will be no problem, I don't plan to use thermostats, I'll use one K probe close to the Saputo biscotto to show me the stone themp with a digital themperature thermometer