Not sure how relevant this is at this point, but it still seems the most people are stating that the recruiter NPC has a cooldown of ten hours after the the three hour event window ends. However, I had noted yesterday that he spawned at around 1PM EST while I was still at work. Didn't expect to seem him come up at all when I finally got logged in, but as I did so at about 7PM EST the NPC actually DID spawn, only three hours after the last spawn window would have ended. I still don't like the fact it despawns at all, but this does indicate that the event occurrences aren't as infrequent as many had been led to believe.

As for the event itself, it was definitely as chaotic as others mentioned. Even though I got killed off a few times by some cheap shots, it was still pretty fun though, and I managed to get both sets of earrings. I can only imagine how much more hectic these city-state invasions were back in 1.0 though lol.