You know what. No President is ever ready to be President. Presidents are made as they serve in their first term of office. They mature, through exposure and experience into statesmen (or stateladies).
Nothing can quite prepare someone to run a country.
You are unique. Your unique combination of strengths, experiences and education has prepared you as best as it can for your new role, job, task, project or adventure.
Go and start it. Do it. Sign up. Start delivering. Start serving. You'll learn the rest as you go.