I always use plenty of lube during assembly, so the engine's well oiled before starting. I pre-mix about a gallon at 20 to 1 for the fuel tank, start the engine on that, then hold the throttle actuated pulley on the oil pump wide open as soon as it starts. This plus a bit of throttle should move the oil along to fill the injector lines within a minute or or so. Once I'm sure the pump is working I add regular gas to the tank to dilute the pre-mix. This will run a bit heavy on the oil till the next fill up, but that's not really a bad thing.