Good advice, as ever, from Oliver Burkeman:
The 70% rule: If you’re roughly 70% happy with a piece of writing you’ve produced, you should publish it. If you’re 70% satisfied with a product you’ve created, launch it. If you’re 70% sure a decision is the right one, implement it. And if you’re 70% confident you’ve got what it takes to do something that might make a positive difference to the increasingly alarming era we seem to inhabit? Go ahead and do that thing.