I would second this entirely.
I have only ever settled on a storyform after the first draft is complete. And when I do, the variations of that storyform will seem obviously correct, like, "why didn't I see that before!" level of obvious. And yet, I didn't. I never do.
But by now, I trust that if my intuition is interested enough in a story to drive me to work on it, that's because there's a complete storyform in there somewhere. I can trust that it'll emerge in the end if I give myself space to explore my imagination without boxing myself in too quickly.
With that said, there's nothing wrong with picking a storyform to guide you through the writing process if it helps give you direction/keeps you motivated. Just don't clamp down on it too hard; use it as a stepping stone to get to a draft that works. Once you have a draft that works, reexamine your storyform and adjust it where necessary to reflect the story you told, instead of the one you thought you were telling.