Wed & Thurs are the best to have more views/reach and be product of the day.
Mon & Tue give you more change to be product of the week as you can collect upvote for the full week, but competition is also higher.
I think overall Tuesday is the best day.
It's one of the biggest day of the week with Wed & Thurday but you also collect votes after the launch to be in the weekly newsletter.
Weekends are obviously less crowded but it can be nice for a small side project to stand out!