Obsolete date & time when printed. How can I set this up?

I work at an academic facility which is regulated by the FDA. We have standard operating procedures (SOPs) in PDF format which we need to controlled, meaning, if a PDF of an SOP is printed, I need to automatically stamp it with a "Print date/time" as well as an "Obsolete as of: date/time" which is 7 days after printing. The key to this stamp is that it is automatically updated with the requisite dates and times. I attempted to use a custom stamp, however, it wouldn't automatically update the dates/times.