I can't stand being late. Hate it. If something starts in 10 minutes and is a 5 minute walk, I'm leaving now. Because of that, I often leave 20 minutes early to get to my class, which is 10 minutes across campus. I have to set up my computer, which kills some time, but I am often left with 5 or so minutes before class, Standing in front of the room while the students file in and get things sorted.
I actually find this time pretty awkward. In a smaller class I can shoot the shit with some of the students, despite the mild look of horror they have at being chatted with by their professor. The larger classes are worse though, since I don't really know many of the student's names at this point in the semester. They chat amongst themselves and I... do what?
I find I wander a bit and maybe even hit the bathroom, or read the posters in the hallway for the tenth time. Sometimes I'll look through the preview thumbnails of the slides just for the hell of it, but I always feel completely unnatural up there. Waiting. If speaking publicly made me nervous, I'm sure this time would be excruciating rather than just merely awkward.
Despite this, I can't bring myself to leave later. So what do other people do with their pre-class limbo?