I don't think that the timing does matter a lot. Let's be honest 75% of all votes on the blockchain are auto votes.
You can try to post once at noon and see if this makes a difference!
Also I would wonder when 2 authors post the exact same post as a test. You will probably have one which will be voted by curation trails while the other wont get those votes.
Yeah, that is probably true. I've seen my rewards drop quite a bit when services like hive.vote are down for the morning or whatever.