"There is absolutely no reason to signal to the enemy when and how, and for how long, you plan to strike them -- none. As I’ve said before, you don’t send out a save-the-date card to the enemy." (Mitch McConnell)
Actually this is a rather good idea. A good idea along the lines of what Žižek says about the best horror films: they tell you they will horrify you, then they do. It actually increases the feeling of surprise.
Or, as one might say to one's children's before actually going berserk, "I am about to go berserk." That often does the trick.