If you fill through the large center hole, in 1-2 minutes the oil will flow through the filter media and occupy the space outside of the filter media (between the media and the canister). So IMO it's not necessary to go to such lengths to fill the filter exactly to the brim through the small outer holes, there's only a small airspace to be filled here and only a fraction of a second gained in oil pressure buildup. As long as the filter is primed with oil, I say it's good enough and I gotta draw the line somewhere LOL. But of course do whatever you want.