Your cartomizers look like they have a small center whole and a foam wrapping, right? Those shipped with Boges that last I saw them.
If so then hold your carto at a 30 degree angle and drip down the inside outer whole so it soaks into the white roam. Drip ten drops and slowly rotate it to the other side and do ten more. If they're completely dry you can get between 20 and 25 drops without over-saturating them. With practice you start feeling out the 30-drop range but not yet.
After you vape a while you can top them off the same way with 5 to 10 drops every so often.
Good luck! -Magnus
Just to add on to what Magnus said, the threaded part, where it mates to the battery, keep the condom on. If you take a bent paper clip or a binder clip (something L shaped) and pop off the soft rubber cap (the mouthpiece), you can see the filling. Drip liquid down in there, keep it on the fill portion (white fluffy stuff). The condom end, at the threaded portion, will keep juice from exiting out that side. I usually drop about 10 drops, rotate it in my fingers, drop 10 more drops on the dry (or more dry) portion of the filling. Put the white soft rubber cap back on, screw into battery, enjoy.
Another thing I like to do, with the condom on, is swing the carto in a circular motion (centrifugal force) to push the liquid towards the condom/threaded portion. This allows a full fill. Alternatively, you can use a syringe to push the liquid all the way to the bottom.
Looks like I should add this one to the list of stuff Dog and I should do
