Пример: time.php
var a = '11/09/2017 08:00:00';
var b = '11/09/2017 12:00:00';
var c = '11/09/2017 16:00:00';
<script class="source" type="text/javascript">
<?php include("time.php"); ?>
$('.countdown').downCount({date: a, offset: +3},function (){
function xx(){$("#start").click();}setTimeout(xx, 1500);
});</script>