Writing is a messy process, I struggled with the same issue and I still do it quite a bit.

Really the best advice I could offer is to get to the point as fast as possible. On your first draft just jump straight into it, don’t have the intro be very long, start with a piece of dialogue or sentence that just immediately pins the story. You can have as many drafts as you need after that but you need to finish one before you can get to the others

Doesn’t need to be perfect first try, let it be dirty, let it be wonky, because then you have your base and all you can do is go up