Showing Created Date of Document

I am using Office 2016 on my Mac. I used to use LOTUS 123 back in the day..... lol lol lol

I have created a worked sheet template that shows created date and edited date.
am bit confused as to which formula I should use.
NOW or TODAY

initially I want the created date to be the one showing as date I created document
but edited date to change each time I open this document.
there are no columns to be added/calculated

can anyone help?