From the answer to the question Is the Han/Leia vs Luke/Yoda timeline in The Empire Strikes Back broken? :
We also don't know how much time Luke spent training.
I tried to check some references like Luke and Yoda related section on their Wookieepedia articles, but there is not even a clue of the amount of time he spent there.
Is there any canon information on the subject? Or any extrapolation of how long Luke's journey on Dagobah was? Was it a day? Several weeks? Some months?
Given the extended universe canon, Hoth to Dagobah is probably a base duration of a few hours at most. They're nearly adjacent, according to the Essential Atlas maps.
Far more important is the travel time to/from Dagobah by Luke. The X-Wing has a week of consumables according to Wookieepedia and a x1 Hyperdrive. Since Luke makes it from Hoth to Dagobah and back to Bespin with under a week of endurance, this puts a much longer trip at 3 days each way or so. Moreover, Luke has the fuel to meet up with the fleet following this, reducing it further.
We don't know exactly how much time it takes for them to make the trip, but we do see Leia change clothes between Hoth and Bespin, so most likely, it was over a day... but with a x10 hyperdrive, that means only at least a 2 hour base trip time. There are implications of a period of time working on the Falcon before Vader reveals himself - and then a period of being tortured. A period of torture implied in the novelization to be high single digit days before Lando works up the nerve to talk to them.
We can see several levels of costume change on Luke, as well. The day he arrives, it's nightfall, and he eats with Yoda. We see portions of the next day. We see a change in costume indicating time passing. We then see Luke in the Tree. We see even more distress on the garments. We see Luke talking with Yoda about Han and Leia suffering. We see a change in outfit to a flight suit, and departure.
We can take as implied that there is at least 2-3 days between costume distress levels in the training. That gives us a few weeks. It's more likely that it takes longer than that.
We have also the Falcon's travel time. It's not much, tho' - even though the Falcon has a maximum of two months consumables, it's travelling on a backup hyperdrive. Backup Hyperdrives are, according to several sources, limited to several hours range... so we can't even account for missing time that way.
In any case, to make things match even a couple days per costume adjustment, the hyperdrives need to be pretty fast.
Also, it is worth noting that anything past about 12 hours makes for pilots in cramped cockpits having various forms of distress - it's hard to sleep in a chair, and in flight relief units are generally only good for urine.
I'd put my estimate between 7 and 21 days of training with Yoda, and about another 2 days of travel time for Luke
Let's try to figure out the time it took the Falcon to arrive at Cloud City without the hyperdrive.
According to Wookieepedia, Hoth is at 50,250 light years from the core, and Bespin is at 49,100 from the core. It doesn't give the exact distance between them, but the lower bound is 50,250 - 49,100 = 1150 light years. I will stop any calculation here because the numbers are ridiculous, estimating the sub-light speed of the Millennium Falcon is pointless and any attempt to estimate the travel time this way is doomed, as it would take more than 1150 years to go there at sub light speed.
All of this is caused by a bad understanding of distances in space by Lucas and other writers who made up these numbers. The numbers may have made sense if Bespin and Hoth had been in the same star system, but it looks like that's not the case.
This was retconned later by adding a backup class 10 Hyperdrive, witch is extraordinarily slow, to the technical specifications of the Millennium Falcon. But still, we have no idea of how long it took to the Millennium Falcon to go to Cloud City with a class 10 Hyperdrive.
However, Star Wars Episode V: The Empire Strikes Back starts in 3 ABY and Star Wars Episode VI: The Return of the Jedi starts in 4 ABY, and there are other events between the movies, which are placed around 3,5 ABY.
So all we can say for sure is that Luke's training time with Yoda could have been anything between about 30+ minutes (i.e. the amount of time it takes on screen) and six months.
Luke wasn't trained in the conventional way, which took years of training and trials. Luke was eager, he felt a strong urge to become a Jedi. It was his destiny. With a gift like none other before him, he managed to resist the dark side.
While Yoda told him to stay and complete his training, he rushed off to help Han and Leia.
Initially, his training (probably) lasted up to a few weeks or so, before he went to the Cloud City. There is no doubt he was a special case, as even Vader (Anakin) himself told Luke that only he can defeat the Sith Lord.
His training time on Dagobah could be measured by the time it took the Falcon to arrive at Cloud City without the hyperdrive (no warp). It is not specified anywhere what this time is, but there are speculations that it took them up to a month to get there.
