Hmmm. Let's see if I can break this down ...
Phase 1 (approximate time - 30 years) ... pretty much self taught
Phase 2 - (2 years) formal training - as a student in the photo tech program at the local junior college. (I got to do this because the VA determined that I was eligible for re-training (I'm a disabled Viet Nam vet), and told me I could take any course I wanted. So, since I already had a B.A. and graduate level work in Special Ed., I, of course, chose a photography course. Hey! Why not! It sounded like fun!)
Phase 3 - (4 years) Formal also ... except in this case I was teaching Digital Imaging at the University. And, as almost anyone can tell you, the best way to learn something is to teach it to others. (You don't really need to know how I went from being a 55 year old junior college student to adjunct professor at a University overnight.)
Phase 4 (which actually overlaps both 2 & 3) - Some of both, because I was working part time in a Camera shop (Both Nikon and Canon Pro Dealership) in sales and as a digital restoration specialist.
Phase 5 (today and for the past two years) Still developing info on my website (teaching): spend a good deal of time reading and practicing what I already think I know and developing new processes for my work; and I do a lot of one-on-one and small group tutoring (which is more of that teaching-to-learn thing).
OK ... is that confusing enough? And I guess I forgot to mention one small thing - my dad was a professional photographer/writer for most of his life.