Mondays could also work, since it would allow people an extra weekend to finish what they want to show. Also it will allow them to procrastinate at work.
I'd say the Saturday after the paycheck closest to the 15th. People on bi-weekly pay schedules have funds again and it's counter cyclical to the 'Who's Hiring' threads.
Sunday might be good because then the question "what are you working on" is associated with what you might be working on over the weekend, i.e. things you're doing for curiosity, fun, or obsession, rather than a workaday job.
