I'm planning on running a game of Dread for the first time this weekend, but some people have conflicts and we can't start until 9:30pm. Obviously it's nice to start a horror game when it's dark, but I live on campus and quiet hours are strict (1am), plus I'm planning on running it for RPG newbies who may not wish to stay up late to have the story resolved. Is a 2-3 hour game (including chargen) unreasonable?
You can manage a 2 to 3 hour game depending on the pace you set. See the Pacing section on page 30 of the rulebook on details for how frequently to call for pulls to accomplish a particular game time and adjust accordingly. Also see page 49 for some tips on how to split your story into acts of an appropriate duration. Essentially, you dictate the length of the game by how much content you include and how frequently you call for pulls.
The recommendation for a 4 hour game is to call for a pull every 5 minutes to ensure that 1 player is eliminated by the end of that period. If you want a 2 to 3 hour game, I would recommend trying to call for a pull slightly more frequently than that, but all that does is hasten the first tower collapse. You also have to ensure that the pace at which you drive the story is matching the feel of how dangerous the tower is. Ideally, after about the 2 hour mark you can ramp up the story threats while simultaneously demanding more frequent pulls to try to force a collapse by the time 3 hours have elapsed.
This all depends on the participation and level of comfort of your players. If it is your first session with new players, they will be getting to know the game and might be slower, especially if they have never played a storytelling game before. In this case, you should design a very short story. Basically, don't think of telling a typical 1.5 hour horror movie's worth of plot. Think of telling the equivalent of a 20-minute episode of a horror show. The players will probably drag that out. It's better to end earlier than intended on a good note and leave players anticipating the next session than to feel compelled to drag a session on way too late because the plot you had planned is not yet resolved.
I believe that the intended game time is a single session of 3 to 5 hours with 4 hours being the most commonly cited runtime in the book. However, the game supports ongoing stories across multiple sessions, and if you are willing to do multiple sessions then you can pause the game at any narratively appropriate time and resume it in another session. I have conducted a multiple session campaign that lasted several months, with sessions of 3 hours each time, and it went over very well. This might be a route to take if you can plan a bigger, more sprawling narrative that can fit into more rewarding, bite-sized sessions.