Yea I’m pretty sure 99.9% of contemporary dubstep is quantized. (the beat is regulated by the computer) Just because the Bass drum isn’t playing quarter notes doesn’t mean that the beat is irregular. Just practice counting the beats. Or try putting a track into a DAW like ableton or audacity and use the metronome to play at the same tempo as your song. If you practice counting along to the song you will find that most dubstep follows a standard composition with builds, drops and breaks in about the same position.
I wouldn’t recommend trying to drop tracks in on any count but the 1 at first, that’s definitely a more advanced technique that I think you will find even more difficult than dropping in your new track on the 1 count.
The learn to digital dj fast course would help greatly with this… you should check it out if you haven’t already…