Is there a way to find out if there is a timestamp when a particular cron task is created/added?

I believe the best you can do there is look at the file containing the particular cron job.

For example, if it's a users cron job, you could run:

ls -l /var/spool/cron/crontabs

And you'd see when the files were last modified. But that will only help if it was the last cron item to be added.
-Eric