This infographic from SurePayroll, illustrates peak times and guidelines for Facebook, Twitter, LinkedIn, Pinterest, Tumblr, and Google +. They are all different, but what most share in common is to avoid posting early morning on the weekends, or after 3 pm on Fridays. Start posting at the right time, to get the best results....
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These guides are always helpful but please don't forget to look at your own analytics and see when your customers are engaging with you most.