Strange suggestion. Have never heard of "mentors for hire".

Where do I find one?

Don't worry much about ages. You can always start whenever you want, but of course, the sooner, the better.

You can find some good programming Discord groups for programmers and join to discuss there.

But be cautious with your goal: Money first, or Long term career path to be a good software engineer. There's difference between the two based on your choices.