Hi Phoenix. I just recently wrote a post on my blog trying to help other people with this same question. You can search online and retrieve a variety of different answers by so many different sources and experts. In my blog post, I provided the example of one source stating that Wednesday at three pm is the best time, while another reputable source said that Wednesday is a bad day altogether!
My suggestion is to take a moment and review your prior posts. on your FB page. What posts were seen by more people? What posts generated more engagement? Certainly, the general rule is before work, during lunch, after work and on the weekends, but take a look at YOUR audience to get a better idea of what and when to post on YOUR facebook page. Good Luck!