I've done mine quite a few times like blykins. My usual method is to spin the pump up to pressure for a few seconds, turn the crank 1/4 of a turn, spin up the pressure again and repeat that sequence until
oil comes out of all the pushrods. This way there is no doubt that all the
oil galleys are filled and you'll have instant
oil pressure at start-up. BTW, I use a 1/4" deep-well socket on a 1/4" extension chucked into a 1/2" drill to do the duties. I've even used a speed handle on the same set-up and gotten decent pressure. Lots more work though.
Steve