Is your majority viewership in the United States? Then it's between 3pm and 7pm (depending on age demographic) in whatever time zone you are viewed most in (I'm viewed most in EST). Is it in another country? When are people most likely to have free time there? That's when the peak is. There is no specific peak, otherwise large musical artists would all put out MVs at the same time, large YT people would all upload at the same time. That time would then become utterly useless to you and I, who don't make up the "elite," because everyone's feeds would be completely filled with big names.
Best thing to do is evaluate your particular audience, age group, location, etc, and figure out when they are going to be using YouTube. That's the best time to upload for you.