Put your thumb over the hole and be fast. Your filter has a rubber flap in it to prevent run back (where the oil in the pressure system runs backward through the filter and deposits the caught material in your engine. Also keeps the oil system primed and prevents dry starts, like when you dont pre fill the filter) You always loose a little but not as much as you think. Besides your also supposed to put a lick of fresh oil on the seal. This helps you ensure enough is on it
These bikes are not the space station. Tolerances allow huge fudge factors. The oil system in these bikes are full of air. That is not an issue. If you think it is, then you need to press your kleenex with a steam iron before you blow your nose. But yes. Always rub a bit of oil on the ring. Otherwise if it is dry on application, there is the strong possibility of the rubber ring binding and buckling and therefore major oil leaks. I hate oil leaks. I tore up a 24 year old concrete driveway that did not have a single drop of oil on it. It was just all cracked up cause the fuggen builder did not use any rebar in it and poured the concrete on bare dirt.