When you turn on your camera, the monitor automatically displays the screen that shows shooting settings for normal, through-the-viewfinder photography. If you prefer not to see the display upon startup, set the Mode dial to P, Tv, Av, or M, select Custom Functions from Setup Menu 4, and bring up Custom Function 12. Change the setting from the default, Display On, to Previous Display Status.
The setting name reflects the fact that the camera remembers the current display status when you turn the camera off. Then it returns to that previous status the next time you turn the camera on. So if you don't want the display to appear on startup, press the Info button to shut off the display before powering down the camera.
Although disabling the automatic display saves battery power, having to remember to turn the display off each time you shut down the camera is a pain. So stick with the default setting and then press the Info button to toggle the screen on and off if the battery is running low. Also note that if the camera is set to any of the Basic Zone modes when you turn on the camera, the display appears regardless of the setting you choose for the Custom Function.