IIRC, Korean anniversary is in august (If not, august, then September) and the global anniversary is around October-November (The reason I mention both is because both anniversaries' are celebrated and bring good rewards.)
The "big" anniversary is next month. It's the one that they usually have all the big promo vids w/ the thank yous and talk about stuff they're working on/planning to release in the next 12 months w/ a few tentative deadlines, tease the content of the next episode in the story, have Q&A, contests, etc. In other words, it's a lot like what they did for their tournament a couple months back, just a little bigger.
There is then another, more modest, anniversary event for the global server release in Nov. That one has a similar log-in campaign, but hasn't in the past few years had the same "pomp and circumstance" in terms of promotional vids and all the extra stuff (in part b/c you're now bumping up close to end-of-the-year holidays).