Automatic timezone for Turkey in 2018 in PHP

<?php

date_default_timezone_set('Etc/GMT-3'); // timezone according to Iğdır
setlocale(LC_TIME, 'tr_TR'); // for Turkish date
if (time() >= 1540699200) { // delete this if after 28.10.2018 04:00 and change the timezone
    date_default_timezone_set('Etc/GMT-2'); // timezone according to İstanbul
}