Well in the book "The Bobby Fischer I knew and other stories", the authors (Arnold Decker and Larry Parr) talk about a man named Arthur Dake (1930's was about when this took place) who didn't learn to play chess until he was 17 years old, he didn't play in his first tournament until he was 20, and by age 21 he was apart of the American World Championship team at the 1931 Prague Olympics.
Guy started playing chess, one year later 2100, 20-22 years old
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Heard here was this guy at a chess club, started one year, lost all his matches, made blunders, then one year later became club champion and switched clubs to learn more. He was rated 2100 KNSB one year after starting chess. He was a university student.
Such a guy is surely to become GM in no time? Heard this at a chess club I once visited.