How much time do we have before it launches to the public?
We've extended the private betas to last about three weeks total. In actuality, if you call the initial launch "week one", the evaluations and discussion happen near the end of week three. We extended the private beta another week because the logistics of launching a private beta and getting everyone together to wrap everything up in two weeks made the deliberations all but impossible.
Usually one week, but if we don't have the site's scope down by then, I would be tempted to request another week in private beta. We don't want to let the whole world in if we don't know what's on-topic and what isn't.