That's how the conversation started, but in my head I took it further. How would time zones affect timing? Audience type clearly affects it, especially when considering local businesses versus worldwide businesses. It's easy to simply say, "test it out," but are there best practices that can streamline the process and come up with conclusions faster? These questions led to these ideas...
Technically speaking, "test" shouldn't be the very first step. You must first analyze what's happening with current posts before trying to improve on them, so analyzing to create a baseline is an essential start. Social media analysis comes in many forms for brands, particularly on Facebook where success can manifest in different ways. Likes, comments, and shares are one measurement. Reach is another, and while it's often affected by the comments, likes, and shares, there are other factors that come into play. Those using Sponsored Posts, for example, may find that their ads perform better at different times than non-sponsored posts.
Facebook allows you to look back at the posts that were most popular. If you're using static posting times, it's possible to look back. You will have to count the posts to determine the exact times; for example, if you know you post at 5:30am, 10:30am, and 7:30pm, then you'll have to isolate the three posts during a particular day to know which was posted at what time since Facebook only shows you the date they were posted once it gets beyond 24 hours.
There's good and bad to the way that the Facebook news feed and advertising algorithms work. Because your past influences your future, it's often hard to go back too far to find success because the influencing factors have changed. You have more or fewer fans, you have been removed or added to news feeds, and the way that you posts become popular is in a constant state of change. Still, you'll need to start somewhere.
Once you have an idea of both the type of content that was most popular as well as the times that they were posted, it's time to make your first adjustments and start...
This is the easy part, actually. Start posting at different times and see what works best at which times. Keep track of your results, of course, and keep in mind a few factors:
This isn't very hard. It just takes patience and persistence. It's your business. They're your customers. Focus on your goals and let the data guide you. If it works, stick with it. If it can work better with some adjustments, try them. Analyze your results regularly and you'll have a much better understanding of how to reach the most possible people.