To be honest, I only have 26 likes on my page and of those 26 people, only about 3 of them ever interact with me on the page. My business partner doesn't interact on the page at all, preferring to let me do all the talking as it were. :)
There does not seem to be a particular time at which I need to post a post - my Etsy items never get likes and the favorites I do get are definitely not from people that have liked my Facebook page.
I have to be honest here, for me, Facebook has never been a good marketing tool.