With OL you will be done a lot of front squats. I think it is common for the front squat to be about 80% of the ATG back squat (not PL style). Mine is 330 Front squat, 405 back squat at 190 lbs.
If you can do OHS to rock bottom that is great. If not work on your flexibility. Before you do drop snatches I would do press unders.
Press Unders: Stand with the bar on the back of your neck with a snatch grip. Descend into a full squat and at the same time, shoulder press the weight. It is finished when you are in a full squat snatch position. Remember, you aren't actually pressing the weight off your shoulders. It should be a smooth motion. You will get faster getting under the bar with practice. Also, hold the bottom position for a couple of seconds to get strong and comfortable in that position.
As a reminder: start with the empty bar for press unders. You have to drill in the technique.
To squat snatch, you will also have to learn to jump under the bar into a full squat quickly. Start with the empty bar. Put up the bar with a snatch width grip. Shrug the bar high and go up on your toes and then quickly jump under the bar into a full squat snatch position. You will have to drill this to practice getting faster under the bar. The elite lifters do this so fast it is ridiculous. You will have to get better at press unders before doing this though.
As always with OL do all your squats: front, back, overhead as low as you can.