Brand posts published between 8 PM and 7 AM, which are defined as “non-busy hours,” receive 14%
higher interaction than those that post between 8 AM and 7 PM, which are defined as “busy hours.”

There is plenty of room for brands to improve on this, as only 18% of posts are sent during “non-busy hours.” When not at work, people are more likely to spend time perusing Facebook and interacting with Page content. Providing the right content at the right time to people is a huge step in the optimization of Facebook marketing, so don’t overwhelm fans when they are busy. By posting early in the morning you also allow your post to increase its News Feed Optimization
during a less noisy time.

(via: For more information on Facebook News Feed Optimization, read the Buddy Media white paper here: http://bddy.me/newsfeed )