Boges are 1ml. This is how I fill, cleanup, settle then keep damp
When I fill the first time (and whenever adding a lot of juice) I hold tissue against the threaded end hole of the carto. Tilt and drip in 18 drops (per ml capacity of the carto) slowly (wait after the first few which may take longer to soak in). Then I wait 15-20 seconds. Then I see how many more drops the stuffing will soak in easily.
Then I do cleanup of the threads, then tilt open end down into a tissue and puff into the threaded end hole to make sure the air channel is clear, then while still pointed down I touch soft tissue to the top of the stuffing to sop up any excess (helps prevent leaks). If you are very concerned about leaks (like if you have auto batteries), put the tissue in first to touch the stuffing, tilt open end down, puff into threaded end.
Then to settle it I let it lay on different sides for 15-20 minutes to spread the juice to every area of the carto. 15-20 minutes is more than enough settling with the thin juices I use. Only the first fill needs some settling time (to make sure every bit of stuffing is damp).
As I vape, I keep it damp. If the vapor seems light or dry or tastes even a tiny bit off or if the carto is getting abnormally warm, I see if it could use some juice. And you can also check the top of the stuffing - if it has gone white you could probably add a bit of juice before heading out or putting a new battery on it etc. I use a plastic or delrin drip tip as a mouthpiece instead of the endcap so it is easy for me to pull that out to check the stuffing or (off the battery) add juice.
I use thin juices, PG w/ 20% or less VG and a couple of Vapor4Life WOW juices. If I get a juice that drops a lot of flavoring sediment, I find a different juice.