I taught myself Objective-C in the 6th grade after I bought my first laptop with money I made from doing contract web development work for local businesses. I made a few simple iPhone apps and and started to appreciate the beauty more than before.
In the 8th grade I started to find school severely lacking and enrolled as a computer science major at a local community college. The courses weren't great, but I learned how to get through a textbook, which I've learned to appreciate.
I got my first proper job at a small (3 person) startup when I was 15. I'm still at this job and have loved every moment of it. We're set to ship our first product sometime next week.
Answers to your specific questions:
* How did you learn to code?
Coding, running into an issue, fixing it, repeat. Books. MIT OpenCourseWare. Community college. And some MOOCs.
* When did you start learning?
Back in the 3rd grade, when I was 7.
* At what point did you start working professionally?
I started doing contract work in either the 4th or 5th grade. Got my first full-time job at 15.