I've been promoting that sketch show I'm in on Facebook, and something occurred to me: For any show, you want friends and family to come to the first couple of nights. Sure, it's great to see friendly faces in the audience whenever. But in order to harness the potential for word-of-mouth, you need to have those friendly faces and their friendly mouths in early enough that they'll have time to promote the show.
Asking anyone to promote something sight unseen is ridiculous. You want your friends and family to actually see the thing they will be promoting. First, they can determine whether or not they should promote it -- Die Grüppe's show is beyond risque in places and not everyone is going to feel comfortable posting the name of the show, let alone encouraging people they know to go see it. Second, the experience of the show is what will create "passionate evangelists." After I saw Re-Animator: The Musical, I wouldn't shut-up about it. Ask anyone. Before I saw the show it was, "Yeah, I'd like to see that." A virus won't spread unless a person is infected, and you infect people with the actual performance, not just the promise.
Why should they come as early in the run as possible? Word-of-mouth needs time to spread. You want your biggest supporters to have as much time as possible to get the word out!
I'm in this show and it opens tonight. Please come see the show! I hope you enjoy it, and if you do I hope you'll tell a friend.