My method is very similar to Charley's--I turn my oven on2 preheat, 250 degrees, for 1 min & then
promptly turn it off, and at that point I switch on my oven light. The oven light will keep the inside oven temp right where it needs to be for proofing bread dough. Got this hint from some genius cooking instructor back in the day, and it has never failed me.