Luke is like his father and like any Skywalker before and after him.
They learn far more faster than most Average LightSider's/Dark-Sider's.
Its been stated thousands of times, Anakin was one of the quickest learning Jedi of all time.
Dooku even thought he was the greatest master of Djem So he had ever seen and was astonished to how fast he mastered it.
And we've all read/seen Luke learn Force Abilities within days. Hell he created some abilities that were unheard of in days and sometimes hours.
"like any Skywalker before him" I didn't know mom was so talented.
A year, lol. That's like someone saying I'm going to go train for a year and then win an MMA championship. I think it might have been longer than a year.