As the Facebook profile has evolved, converting into the Facebook Timeline, our personal social network pages have become just as much about the past as about the here and now. Open up your Timeline and you'll see a chronological list of years making it easy to dip into your previous activity. One of the ways in which you can use this information is to see how long you've been friends with someone on Facebook.
Log in to Facebook and follow a link to the Timeline of any of your friends (from the News Feed or your friends list for example).
Click the black gear icon to the right of the cover photo and choose "See friendship" from the drop-down list that appears. The subsequent page shows your mutual history on Facebook and by scrolling down to the very bottom you can see when you first became friends on Facebook (use the year links on the right to scroll more quickly). Click on the date link within the entry to jump to the individual Facebook post marking the start of the friendship.
Click "More" at the top of the friendship page and enter the names of two Facebook friends into the fields provided. Click "See friendship" to view their friendship page, including the date they first became friends on Facebook.
You can only view friendship pages between two people you are friends with on Facebook. The content visible to you on each page depends on the privacy settings associated with it (images set to private won't show up for example).
At the foot of each friendship page is an option to set the date when two people first met outside of Facebook. If these details have been filled in on the friendship page you're viewing, the entry appears underneath all of the Facebook activity.
Links to Facebook friendship pages can be shared on your Timeline or posted to the Timelines of others. Click "Share Friendship" at the top of any friendship page to see the available options.