Setting the time and date on your camera is important. Some of Final Cut Pro's features require time and date information on the tape in order to function reliably. For instance, if you're capturing DV or HDV using scene break detection, it's important to set the camera's clock before shooting video.
For best results, shoot your video after setting a date and time on your camera's clock. If you've already shot your video, you might find that automatic scene break detection doesn't behave reliably. If this occurs, simply log your clips before capturing, or use the controls in Capture Now to place scene breaks as desired.