I can't believe I have yet to post on this topic as I have been asked a lot about this question. While there are stats out there done by various firms on when and how you should post, it can still be a "crap shoot" if are in to heavy analytics to get the most out of your posts. Having said that, there are some great resources and tools I personally use. HootSuite has auto scheduler which I like as it sends your tweets out based on historical times to reach your masses. Besides the ability to pre-load your tweets and have them go out to all your platforms (paid version), auto scheduler has proven to be a valuable tool. Another item I have read about but have not personally used to the nature of my business is Social Bro. This is strictly for Twitter and if you have a specific marketing firm or a larger Business it is a good tool but for smaller companies, using common sense can get you the same information. It is not free starting at $6.95 a month on up to $145.00 a month.
Getting down to the brass tactics of posting. Research shows the
You can already see why I said that posting can be a "crap shoot" as most small business do not have the resources to be posting at all these various times unless you are a large business with a specific social media employee or have a marketing firm that can do this for you. A scheduler like HootSuite or similar tool can be most helpful in auto loading these times for you and cuts your work load in half. The above information is a guideline done by professional research firms and obviously your situation may be different based on your product or service and your staffing. Experiment a bit and look to see who is responding to or reading your tweets, Facebook posts, Linkedin comments or repining your pins and change your times if you are noticing low responses. Good luck!