I use the following method:
A tip that I use when filling a carto is to plug the center air hole with a wooden tooth pick. This blocks any unwanted e-
juice from getting into the tube that can cause flooding.
I hold the carto at a slight angle, and rotate it around as I drip liquid onto the polyfill. When the fibers look like a slushy drink, I shake the carto down like a thermometer. This produces the same effect as a centrifuge, forcing the
juice down into the carto. I return to adding more drops, and shake it down again. Repeat this process until the polyfill will absorb no more liquid. It is then ready to be vaped. No need to let it sit.