Founders with a coach, mentor or advisor: when did you get one, and what changed?

Something I keep noticing: the founders who seem steadiest aren't the ones with the thickest skin. They're the ones who have someone to think with, and who got that person earlier than I did. I'm curious about the practical side. When in your business did you get a coach, mentor or advisor? Did you pay for it or find it informally? And what actually changed afterwards: the decisions themselves, or how much they cost you personally? Also interested in the other view. Has anyone found that advisors mostly cost money and told you things you already knew?