Prior to H1, I've been working on wall HS slowly getting my wrists closer to the wall, and increasing volume to 5x60s. My shoulders aren't perfectly open, but enough to not be a complete impedance. I would practice different variations kicking up into a freestand HS, but I would always either kick up with too much force and start walking with the hands, or kick too softly, and simply fall down. I tried focusing more on bringing my kicking leg up first and inline, and than gradually bringing my other leg up, and while this helped, it did not fix my issue of continually having to walk instead of simply staying put.
Yesterday I tried a few freestanding HS, and when I placed my hands on the floor I had them slightly arched so the palms were off the floor like cupping (what one normally does to balance from falling forward), and this gave me enough "resistance" that when I kicked up I didn't have to start walking, and all of a sudden I did three consecutive freestand HS for my longest time ever (10-15s).
So if you're in the same boat I was in never being able to stay still because getting the kick up was so hit n miss than try arching the hands a bit instead of starting off with flat palms on the ground.
I will also note that I started H1 a few weeks ago, and it's definitely helping! B)