WoW’s Anniversary takes place in November and runs for two weeks with varying dates each year. In 2020 it runs from November 1 to November 22, earlier than in previous years and a week longer.
A couple of weeks ago I checked the in-game calendar and Wowhead to find out when WoW’s 16th Anniversary would be. At the time it was listed as November 16-30. Now it’s changed from November 1-22. Yes, it’s going now.