Actually, I do an upside down condom fill, since I use flanged cartos and learned it wrong to begin with (I only heard about it, I hadn't seen a video). I fill the condom about 2/3, put the top of the carto part way in for about 30 seconds, then push it all the way in, flip it over and tap it until I see a big air bubble, shake it like a thermometer, pull off the condom and let it sit for awhile. I might do it all again if it looks really dry. Then I top it off with drops, shake again, blow gently from the top into a paper towel & roll up a small piece of paper towel and slide it up the bottom hole to blot, and let it sit for a couple of minutes.
I have no idea why this method works better for me than any other, except that my attention span is so short and my hands too shaky to drip very much accurately.