- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set('Europe/Prague');
$t1 = \DateTime::createFromFormat('Y-m-d H:i:s', '2017-08-30 17:05:29');
$t2 = \DateTime::createFromFormat('Y-m-d H:i:s', '2017-11-30 16:50:59');
$i = $t2->diff($t1);
echo "DIFF: {$i->m}mon {$i->d}day {$i->h}hrs {$i->i}min {$i->s}sec";