He has to do military service, starting November most likely since that is the next recruit drafting month, and ending in the middle of August. If he is the oldest of 3 children, then he will be free in July.
If he's smart and his unit allows it (most do), he can take 2-3 weeks off, sometimes more if the commander is lenient. Also, he can use his evenings off to catch up with grinding, assuming they don't send him to an island in the middle of nowhere with no Internet lol.