Parse PHP, sending notification on a specific date and time

Question

First thanks in advance and sorry for my Google / English. I'm using the library parse php. The code below sends a notification to a particular user. Try to set a shipping date. Receipt notification correctly, but immediately. It ignores the date set in push_time.

¿Someone knows I do wrong?

$format = 'Y-m-d\TH:i:s\Z';

$datetime = date($format, strtotime('+120 second'));
$d = new DateTime( $datetime );

$pushQuery = ParseInstallation::query();
$pushQuery->equalTo('userId', $this->input->post('userId'));

ParsePush::send(array(
    "where" => $pushQuery,
    "push_time" => $d,
    "data" => array("alert" => 'Test message')
    ), true);