Rml, Insert > Date and Time. Select a date format. Check Update
automatically. OK.

If you ever want to convert it to a "hard" date, select the shaded date
field and Insert > Date and Time. Uncheck Update automatically. OK.

You can either insert a date field in which case every document you create
will show the system date - regardless of when the document was created, or
you can insert a createdate field in which case the template will always
show the date it was created, but documents created from it will always show
the date they were created.  In practice, the date in the template is
irrelevant. It is the date in the documents that matters.

Generally speaking you want to use a CreateDate field in a template. When a
new document is created based on the template, that will update to the then
current date. That date will remain fixed in that new document.

See http://addbalance.com/word/datefields1.htm for information on the
different kinds of datefields and how to format them.