FWIW if you look at the history of events, they are pretty much invariably within +/-1 week of past years' start dates and almost always start/end on the same days of the week as the prior year and are preceded by a week on the beta server. So, if you are anticipating an event, look at last years, subtract 2 weeks and start watching for the beta announcement then.
In my time I believe I've only seen 1 or 2 exceptions, both to the delayed rather than early side of things due to back end issues needing to take priority