Life is always more complicated than it seems like it should be. No matter how sure you are that you can get that report done by next Tuesday, something (or more likely, several things) will intervene to make Monday night a nightmare for you. Be smart. If you have the luxury to set your own deadline, give yourself at least 50% and as much as 100% (depending on the project) more time than you expect to need.
Now, here’s the trick: After you’ve established the “official” deadline, give yourself and your subordinates an earlier deadline — one you optimistically hope to achieve. Set assignments, meetings, and reviews accordingly. If things get out of whack, you will be able to make adjustments without stressing. (This will impress your subordinates.)
If you get done on time — before the official deadline — you and your team will look like superstars. This is an astonishingly powerful — and amazingly simple — technique that could really improve your performance reputation. It’s a shame most people can’t get themselves to do it.