For practice I built a small 6’ long platform in the backyard. Its just long enough for my bike to fit on it with several inched to spare front & back. I ride up onto it very slowly, stop and hold a track stand for a few seconds. Then from a complete stop do a wheely drop. This drill lets me work on a couple of things at once (slow speed maneuvering, track stands, & wheely drops). Lately I have been working on doing wheely drops to my left or right side after a track stand instead of straight off the end. I set the platform on concrete blocks and can adjust the height to suit my mood.
I gotta setup something like that...