Linking your channel to Google Analytics gives you extremely valuable insight into your analytics including hourly analysis by day (screenshot below)

You can link your channel to Google Analytics using the following guide:

After the link is complete, come back to Google Analytics a couple weeks later. Click the "Home" menu item, scroll down and find "When do your users visit?". This will give you hourly analysis of when people are visiting your YouTube channel. Look for peak days and hours and use those to decide when to publish (generally a couple hours before peak).