User blog comment:FairyRaven/Fairy Tail Chapter 389: The Twin Dragons vs. The King of Hades, Review and Commentary/@comment-98.218.131.180-20140620180748/@comment-7418318-20140620190426

Enough time to travel back to Magnolia, go to Walrod's place, go from the Sun Village to Walrod's place again and then back to Magnolia (unless he gave them the tree-express again). At the very least I'd say a week, likely more, but certainly not enough for anything like the 3-month training many FT mages did before the GMG, if I had to make a guess.