There has been a great dispute around how much time Luke spent in Dagobah. I've heard "two days", and I've heard "one year". Let's asume it took a whole year for Solo and Leia to get out of Hoth, travel through asteroids, escape from the empire and go to where Lando is, therefore Luke trained for a full year. Luke had a very specific training, and most of it was probably offscreen (like the lightsaber one, I suppose he fought Yoda?).