- time: documentation ( source)
- date_default_timezone_set: documentation ( source)
- strtotime: documentation ( source)
<?php
date_default_timezone_set('America/New_York');
$creationTime = strtotime('2014-05-29 17:30:00');
if(time() - $creationTime < 30 * 60) {
echo 'less than 30 mins';
}else {
echo 'more than 30 min';
}