Countdown Timer Accuracy

?I am using the countdown timer shortcode to display a countdown, which bases the output on the number of seconds remaining until 0. This causes a conflict with sites that cache pages. The problem here is that the output of the page is cached with the number of seconds remaining until 0 at the time the cache was generated, so visitors will not see an accurate countdown on subsequent visits.
I have disabled caching on the page for now to get around this issue, but it would be better to base the countdown on the starting date/time instead. This would prevent page caching from messing up the countdown to 0.