this is the first FR article tagged with the contemporary notion of fake news that I could find (and also that I could recall offhand):
Renegade Facebook Employees Form Task Force To Battle Fake News
buzzfeed.com ^ | 11/14/16 | Sheera Frenkel
Posted on 11/14/2016, 3:53:35 PM by ColdOne
http://freerepublic.com/focus/f-news/3494201/posts
However, buzzfeed had an article about so called fake news on facebook as far back as oct. 20, 2016:
Hyperpartisan Facebook Pages Are Publishing False And Misleading Information At An Alarming Rate
A BuzzFeed News analysis found that three big right-wing Facebook pages published false or misleading information 38% of the time during the period analyzed, and three large left-wing pages did so in nearly 20% of posts.
posted on Oct. 20, 2016, at 10:47 a.m.
https://www.buzzfeed.com/craigsilverman/partisan-fb-pages-analysis?utm_term=.qaB4Wy7A1z#.fdByAdoX23
In turn, the buzzfeed article references an even earlier New York Times article:
Inside Facebook’s (Totally Insane, Unintentionally Gigantic, Hyperpartisan) Political-Media Machine
How a strange new class of media outlet has arisen to take over our news feeds.
By JOHN HERRMAN
AUG. 24, 2016
The “fake news” concept sure seems recent, but it’s getting the downhill snowball effect. Of course everyone (I’d assumed) with some web experience knows you can’t believe everything you read on the internet. There was a time, however, when people did believe that if it was in print, it must be true.