I agree with John and Weemis,
Take the time to heat-up you oven properly. I recommend to start the fire in the front and then move it to the middle of the oven. Every 20 to 30 minutes, move you fire from left, to right, to the back of the oven, ... so you dome and floor is heated evenly. Most importantly, try to always have some nice embers spread over the entire floor during the heating time.
Once you oven dome is entirely white and as hot as you want it, then move the fire to the side. Give it anywhere from 20 to 45 minutes to cool down a little and the floor temp to even out.
Then just keep a small to medium flame to help with the coloring of the top of the pizza.