Unstable Split Jerk? Use This Technique Primer
2-3 sets of this before your jerks will help you dial in your position and balance.
Loading can be anything from the empty bar (and should be no more than that until you can do both movements consistently well) to as much 40% of your best jerk eventually.
Just remember that this is not a strength exercise—the purpose is learning and practicing the perfect positions and movement, so loading that prevents you from doing that is counterproductive, and it’s still going to be so light that it’s not building any strength anyway, so don’t waste your time trying to go too heavy.