When I use the condom method to fill a new carto (Boge), I fill the shorter condom completely full (20 drops or so). Then I just slide the carto down into the liquid. Then I just let the carto sit in the condom until the carto absorbs all of it.
Be sure to watch the vid on filling the J-
tank (ENS web site). Their trick is that putting the cap back in the tank creates pressure which forces liquid into the new carto.
Have you seen "The Fuel Tank" at ENS? Perfect if you like cinnamon flavors.