Why is Night of a Thousand Masks on November 11th?

So, Anonymous (the Hacktivist group) is throwing a Night of a Thousand Masks night. Which, as far as I can tell, is basically where you show up at St. Paul’s Cathedral and reenact the climactic scene of V for Vendetta. Which then begs the question: Given Anonymous’s giant love affair with V for Vendetta, why didn’t they have it on the 5th of November? I’d totally get it if it was currently May or something, and the 5th of November was months away, and Occupy is going on right now and you can’t always wait months to be part of a social movement, but the 5th of November was less than a week ago. Why schedule this event for 6 days after Anonymous’s “day”?

Here’s hoping the Fluther community pays more attention to Anonymous than I do.