I think you are right and I voted your contribution up.
But you don't really think it will work?
Developers were kings once. Big companies turned them into slaves.
I started writing programs when I was 14, on a commodore pet that I found in my school.
Professionally?
I wrote a little software during my master thesis time. This is kind of professional, but it was not the main objective.
I did the same during my phd time (physics).
It was not before 1 year after my phd, that I earned my money with software. Nowadays, my primary work is developing software, although I am a scientist.
So the answer would be:
30+ years, when I count my first programs
20+ years when I count from my first professional programs
10+ years when I count from working professionally and full time on software
I voted 10+, but I suggest, you restart the poll with a more precise question. (scientists can be a nuisance, aren't they?)