Afficher la page qu'à partir d'une certaine date/heure

index.php

<?php
date_default_timezone_set('UTC');

$tz = 'Europe/Paris';
$timestamp = time();
$dt = new DateTime("now", new DateTimeZone($tz)); //first argument "must" be a string
$date = $dt->setTimestamp($timestamp); //adjust the object to correct timestamp
$date = $dt->format('Y-m-d H:i:s');


$date		= strtotime( $date );
$date_mel	= strtotime( '2017-11-07 20:30:00' );

echo 'Date : '. $date .' / '. date( 'Y-m-d H:i:s',  $date ) .'<br>';
echo 'Date MEL : '. $date_mel .' / '. date( 'Y-m-d H:i:s',  $date_mel ) .'<br>';

if( $date < $date_mel ){
	echo 'Attente';
}else{
	echo 'Go!';
}