It depends... If you're asking the exact time to publish, it's depends on your target audience time difference (sorry, forgot what it called). Just made an estimate time of when you think is the best them someone would have the time to relax and check the FRESH section.
For the day, it is usually the weekdays where it got slower traffic, but it'll made you stay on the FRESH section longer, and if you Published on weekends, it does the opposite.
But that is on theory, so you need to experiment it yourself, I guess? Well, best of luck, mate.