I don't need to slap, knuckle, or otherwise stretch my dough at all unless it's really cold. Typically, I gently press top to bottom (protecting the cornicione), flip and rotate 90 degrees, gently press top to bottom, flip and rotate 90 degrees, press gently to to bottom, then lift and place it where I will top it. When the lifting, the weight of the dough stretches it a bit. At that point, it will be about a 10" diameter. After I load it onto the peel, I will stretch the cornicione out to 13". This way, you have complete control over the center thickness. Of course, this does not work if your dough is tight.