If I follow your original question correctly, you are not asking how to get a timestamp, but rather, how to pass that timestamp (or anything else) from a posting cgi script to a displaying cgi script.

Let's call them show.pl and post.pl and map out the transitions:

show.pl spits out a page with a form in it
	which displays in the user's browser. User responds and according to the form action the data is sent back to post.pl
which processes it and then spits out just an http location: header line specifying show.pl's url and includes in the url the needed data (either in the extended path or the query string)
	which goes to the user's browser and quickly bounces back
to show.pl which retreives the needed data using CGI.pm and posts the page accordingly

The added advantage of the bounce technique is that it prevents the "Repost form data" message if the user hits the reload button.

If this is what you were looking for, you might find these further details helpful also.