What we've done in the past is that we will say that we will start at 4 and end at 6:30. That turns to 7:30 and eventually to 11:00. We eventually just had that listed on our official calendar.

As for our mentors, we're not allowed to be in the space without one (because of safety). That, we've never had a problem with, but they have to stay with us into the late hours.