How many days pass during the first part of Konosuba episode 4? The first half of Konosuba episode 4 shows a montage of Kazuma and Megumin training, leading us to believe it went on for a long time.  Long enough for the seasons to change several times.

It seems to me that it wouldn't take too many for the event that happens halfway through the episode to happen, so I don't think it was a year like was implied with the changing of the seasons during the montage.

How many days has it been?
Actually, if you look closely at that episode, Kazuma's explanation of the different setting was of weathers, not of seasons. It was meant to show that they trained regardless of what weather it was during the day. So, basically only days passed, not seasons.

To further reinforce this, Volume 1 Chapter 3 of the light novel directly states how much time passed. To quote, 


  Thus we spent a week in pleasant explosions. Then, one morning…