Overhead Step Up

I am a new lifter interested in Olympic lifting. After a two week break-in period, I will begin a program based on the deadlift, press, RDL and overhead squats (for the snatch), and front squats (for the clean). I can power jerk OK, but I’m just getting comfortable with the split jerk. I thought a good assistance exercise for the split jerk might be an overhead step up. Have any of you ever done this?