When to Post on Facebook, Twitter, Tumblr for Maximum Effect [Study] - Search Engine Watch
Posting content at specific times of the day and days of the week helps marketers better reach their audience and see the virality of their content maximized. Bitly shares insight into the optimal posting times on Facebook, Twitter, and Tumblr.
9 May 2012 ... The best time to post content with a link on Twitter is 1 to 3 p.m. EST Monday to Thursday. Over on Facebook, between 1 and 4 p.m. mid-week ...