Parent link need to go first child submenu

I found solution here

Create template for parent pages:

<?php
    /*
        Template Name: Redirect To First Child
    */
    if ( have_posts() ) {
        while ( have_posts() ) {
            the_post();
            $pagekids = get_pages( "child_of=" . $post->ID . "&sort_column=menu_order" );
            $firstchild = $pagekids[0];
            wp_redirect( get_permalink( $firstchild->ID ) );
        }
    }
?>