Oh, BTDT! It's why I keep piping up about it. I know firsthand how scary it all seems. But happily, I can also tell you from experience that you're more scared than you need to be.

Worst case: you start out one direction and it doesn't work. <shrug> So you change! No petitioning the queen or making a federal case of it. You just do something else, using what didn't work to help steer you in a better direction. No big deal.
As long as you don't throw up your hands in despair and quit, it's all fine. (And never feel like you have to finish something just because you started it. When it's not working, it's okay to do something else.)
Just make sure you and your child both accept from the start that you WILL make mistakes. If you know that going in, it will make the whole process easier.
Homeschooling is actually a really good anti-perfectionism exercise, for both parent and child!

Very healthy for us all!
And, yes, you should see my NOT clean house...
