According to this infographic from bitly the ideal times to post on Facebook for maximum engagement are during midweek from 1:00PM to 4:00PM. Twitter was pretty much the same deal, except Twitter’s “prime time” ends earlier at 3:00PM.
But what about the weekend? Many people just do not have time during the week to engage. Markets and industries are all different. Does your industry adhere to these timelines? There is only one way to find out. Post on the weekends and measure the results.