แก้ไขหน้า index.php ใน Wordpress ยังไงดีให้มันขั้นหน้าแรกก่อนเข้าหน้าหลัก

<?php
/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

session_start();
if ( ! isset($_SESSION['already_in'])) {
	$_SESSION['already_in'] = 1;
	header('Location:'.'/popup.php');
	die();
}

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require('./wp-blog-header.php');