Insert current date and time quickly in a Word document

   Alt+Shift+D   - Current date.

   Alt+Shift+T   - Current time.

To avoid changes of a current date or/and time in the completed document, you can use Cut + Keep Text Only combination:

   1.  Select pasted Current Date or/and Current Time.

   2.  Do one of the following:

• On the Home tab, in the Clipboard group, click the Cut:
  
• Press Ctrl+X.

   3.  On the Home tab, in the Clipboard group, in the Paste list choose Keep Text Only:

See also this tip in French: Insérer rapidement la date et l'heure actuelles.