An old maxim of combat is that no plan ever survives the first ten minutes of contact, and many times, this is true. One of the greatest military strategists of the modern era, Colonel John Boyd, studied many successful generals who practiced the art of "maneuver war", such as Ghengis Khan and Erwin Rommel. What he discovered was that successful maneuver armies not only have plans to accomplish their primary objectives, but also have "branches" in their plans, to allow for greater flexibility. For example, junior leaders not only have their primary objectives, but secondary ones as well, should the primaries not be attainable. Boyd also noted that great armies and organizations (much like animals) were not necessarily the strongest armies, but the ones which were the most responsive to changing conditions on the battlefield.
All operations involve some degree of the unknown, and will be subject to forces well outside of anyone's control. This week, I had just that sort of operation. The plan and the timeline were in a constant state of due to a number of factors--sandstorms, broken aircraft, meetings that go on forever, you name it. Just when you think you have the plan finalized, a sandstorm delays things for days.
Everyone involved in the operation can easily get frustrated. But the frustration that occurs, the blaming of one another when things don't happen as planned, all this leads to what Clausewitz called "friction". This is exactly what the maneuver warfare artist seeks to exploit in other armies, and exactly what we need to avoid in our organizations.
So relax, accept the change, and move on with life. Nothing is ever certain. Just execute a superior OODA Loop and you'll be all right.