The Timeline is a visual story of your life, which allows you to chronicle every step of your existence from time you were born.
Once you get the update Facebook gives you a 7-day grace period before your friends see your Timeline. You will have this time to un-tag, delete and edit your posts before you are live. You can even promote your favourite events and activities on your timeline.
If you want to try Timeline right now, you can do so by heading over to the Timeline Page and selecting the Get Timeline button at the bottom of the page