If you've been following my posts, you already know I'm a huge proponent of utilizing your analytics, as well as industry-related research to find the optimal times to post on Facebook.
Linchpin designed this great infographic that illustrates the best times to post on Facebook, based on industry. If you're in the health industry, schedule your most important Facebook posts on the weekend. (There's an error in the infographic -- the best days are Saturday and Sunday, not Monday.)
The data was taken from Buddy Media analyses based on 1,800 major brand Facebook pages between April 1 and May 31, 2012.