Hi Jason
I managed to solve the problem by coming at it from a different angle - I made a form with hidden fields to pass the value and timestamp to the database and a Submit button with a value of "Generate PDF". On submit, it then displays the actual download link along with a message saying "PDF generated on [date, time} in a field using a Show If to only show it when the value in the dB is "1". It means that when the user revisits the page, they can see that they already generated a PDF and when.
Thanks anyway!