According to Facebook's rules, they will wait two weeks before actually deleting it. This seems reasonable. I've been on the other side of this, and it saves them the grief of having to deal with people who impulsively delete their accounts and then decide they want them back. Two weeks is enough time to decide if you really mean it.
For me it was not an impulsive decision. I hadn't logged on to Facebook since we discovered that you couldn't log out, starting with this post on September 24. But I had never been a big Facebook user. I think this is partially because I'm an early adopter and Facebook was developed for college-age people, and I'm not part of that group.
I just emptied out the mailbox that accumulates all the Facebook emails. It's true, there are people who seem to depend on Facebook to reach me. Well, I've missed there messages for over a month. We'll all survive this.
Bottom-line: I know from experience that it's bad to depend on a for-profit company to give me a free service that is supposed to not feel like it's free. Facebook makes it difficult or impossible to maintain an archive copy of the stuff you post there, so, knowing this, I never posted anything there that wasn't a copy of something I posted elsewhere or something I just didn't care about. And I hate the idea that they devise ever-more-sneaky ways of tracking you on the web. And I'm not one of the people who uses the word "hate" when I mean "mildly dislike."
But I'm not ruling out never going back. It's possible they'll add a feature that I feel I have to check out. Or they may relax their data export and import policies. Or there might be a law passed that everyone must have a Facebook account. All of these would be reasons why I might create a new account after my account is deleted, two weeks from yesterday, on November 23.