[рони]

rodiony4,

$(function() {
     var remaining = 5;
     var myInterval = $("#tiktak").is(":visible") && setInterval(updateCountDown, 1000);

     function updateCountDown() {
         $("#tiktak").text(remaining);
         remaining--;
         if (remaining < 0) {
             clearInterval(myInterval);
             location.href = "http://mysite.ru";
         }
     }

 });