Here, then, are 10 things you need to know before the floodgates open.

1. Facebook's usernames will be given out on a first-come, first-served basis.

If you're dying to get "johnhenderson," you'd better not go to bed early. Facebook will start handing out usernames at precisely 12:01 a.m. EDT. Odds are, most common names will be gone by 12:02.

2. Once you pick a name, it's yours for life.

Each Facebook account gets only one username, and you can never change it. You can't transfer it to someone else, either. Even if you delete your Facebook account, Facebook says the name won't go back into the pool.