people tend to spread out their uploads, like monday and thursday etc. I've looked at my best times to post, and monday is the worst, so I tend to aim for friday and sunday. Wednesday and saturday could also be something to go with seems the "new" label on content tends to have a 48 hour lifespan. I generally don't like posting too much next to each other because each video gets a window of 48 hours it seems, 48-72 hours, so my feeling is if you post something else within 24 hours, it can impeed on the out of the gate performance of the previous video.
Look into your analytics for your demographic. How old are they and where are they from? My biggest audience is America, India and Portugal so I try to get all 3 time zones in my publish window.
If your audience is mostly adults, then you have their lunch break, and after work/after dinner period to get them watching, or in the morning afternoon when people travel to and from work. Adults are probably less likely to watch on weekends because they spend time with their families, going out to do shopping etc, so try and publish when they are at the computer and have time to watch videos.
If your audience teenagers or maybe university aged students, you basically have lunch time and end of the day to get them on YouTube, but remember people going to school have homework and assignments, so your best option is to post on the weekend to get them when they're free
Then you put that into which country they're from, so if it's india for example, Publish when it's around 11am or 5pm in India on a weekday, or any time on a weekend, so long as it's during the day. Then just apply that theory to whatever region is the dominant region in your audience.
