how to set day count down in jquery?

Question

I have a jquery of day count down but i am not able to understant it. the out put of this script is-

476 days , 1 hr, 11 minutes, and 32 secends

and that counting down. script is-

    <script type="text/javascript">
    $(function () {
    var austDay = new Date();
 austDay = new Date(austDay.getFullYear() + 2, 0, 0);
 $('#defaultCountdown').countdown({until: austDay, layout: '{dn} {dl}, {hn} {hl}, {mn} {ml}, and {sn} {sl}'});
 $('#year').text(austDay.getFullYear());
 });
    </script>

can any body reset this so that it displays- 8 days, some hr, some minutes, some sec basically I want to set count down for 18 .september.