I tried different times, from 10 p.m. to 7 and then 6 p.m., considering my timezone (Italian time) i tr to publish my videos at a time that can be good for people to watch. The problem is that if I upload around 10 pm it would be something around 2 pm in america that is good but it would be a little late for example in UK so I'm still struggling a lot for searching the right time, in fact I'm obtaining low views (even considering my channel size) so I don't know if it's time's fault even if I don't think that.
In the end it's preferable, in my opinion, something around the first afternoon (even if you can collide with other big youtubers uploads so it's an hard choice).