Вот то, что я искал в случае, если это поможет кому-то еще.
function countdown($year, $month, $day, $hour, $minute)
{
$the_countdown_date = mktime($hour, $minute, 0, $month, $day, $year, -1);
$current = time();
$difference = $the_countdown_date - $current;
if ($difference < 0) $difference = 0;
$days = floor($difference/60/60/24);
$hours = floor(($difference - $days*60*60*24)/60/60);
$minutes = floor(($difference - $days*60*60*24 - $hours*60*60)/60);
echo "Checkback in ".$hours." hours and ".$minutes." minutes";
}
countdown(2016,1,1,12,0);