I got the dates screwed up. Internets says 11/16/12 at noon PST this thing kicks off. I suspect the patch that morning or previous evening.
Events:
November 15, 9:00 PST (17:00 GMT) Free trial period begins
November 16, 12:00 PST (20:00 GMT) Defend Lion's Arch - defend the city against the karka
November 17, 12:00 PST (20:00 GMT) Retake Lion's Arch - drive out the karka. Discover a brand new map - Southsun Cove, a new island located in the Sea of Sorrows
November 18, 12:00 PST (20:00 GMT) An epic multi-hour one-time event - Battle the Ancient Karka in Southsun Cove
To summarize, it looks like:
Invasion comes to LA. We get ass kicked and fall back. We regroup to retake LA and then take the fight to them.
We've all seen this scenario before. It will be fun to take part in the story for once.