There's a reason so many investors and employees try to promote a culture of transparency at a company... Because to do anything less is a sign of (a) gross incompetence, and (b) greed.
It is often extremely uncomfortable to stand in front of your employees and say "Hey, we've got 3 months left unless we hit this milestone. Let's work together on this and if you can't commit, we'll help you deal with it." It sucks to say and feels terrible, but better than an overnight blow-up.