1. Right click anywhere on the desktop and choose New -> Shortcut.
2. Type timedate.cpl Press Next
3. Name the shortcut as what ever you want. click "Finish." You will see a time-date shortcut on your desktop.
4. Right click that shortcut icon, select Properties and type "T" in the box that says "Shortcut key".
Now, Ctrl+Alt+T to see the current date and time on your screen.Esc to close that Window.
If your in Microsoft Word, type Alt+Shift+D to insert the date while Excel users can type Ctrl+; or Ctrl+Shift+; for the current system time.
Ref: Digital Inspiration