Same boat as the OP. I didn't fill my carto first and after a few hours tried a puff...horrible dryburn/burn taste. Only did it once and hope I didn't burn the carto.
I will try filling the carto and going from there. I did do a few puffs without firing thinking it would pull some juice in, but even now after about 18 hours the inside is still looking dry. Shouldn't it after a long time eventually wick inside the carto? If it hasn't yet will that be an issue going forward?
Using a double holed carto with 80PG/20VG juice.
You've probably burnt the carto badly. I've gotten a slight burn from a couple that ended up working but would not wick well. I know it's frustrating, but once you get the hang of what works for you and your juice, it's well worth the effort. Almost everything with ecigs has some learning curve and fiddle factor. Once you learn the ins and outs and get a sense about the "personality" of your equipment, it's pretty easy.