UPDATE: According to Inside Facebook the Timeline opt-in period will last for a “few” weeks BUT:
From the time users activate the new profile, they will have seven days to review their content before anyone else will see it.
Without user consent, Facebook announced today that it would post archived user information, making old posts available under Facebook’s current downgraded privacy settings. Users have just a week to clean up their history before Timeline goes live. The surprising announcement follows a recent decision by the Federal Trade Commission which found that the company had engaged in “unfair and deceptive” trade practices when it changed the privacy settings of its users.
See Also: More From EPIC About Privacy
See Also: Timeline Now Available on Mobile
The Timeline is live for those who wish to opt-in today, it will give users of the world’s largest social network one week from when they activate the new profile before the Timeline kicks into gear.