Anytime you go to weld steel you will want to be at welding temp. 2335-2350 or by eye; when the borax bubbles on the surface.
When you are drawing the steel bring the temperature down to a working temperature of 2100 or so. I find the billet will hold together better by using the reduced temp. Flux early as the heat rises so you get the steel sealed before you get carbon scale build up. If you are using kerosene to prevent ox. on the steel surface, do not move the steel around inside the forge, after the kero is applied, you can damage the jacket the kerosene produces and let ox. contact the steels surface.
Flying flux is like napalm cover all skin surfaces and remove anything combustible from the area.
Have fun and best of luck to you, Fred