gistfile1.php

<div class="shows-list-wrap">
<?php
  $currentdate = date('Ymd');
  $args = array(
    'posts_per_page' => -1,
    'post_type' => 'concert_type',
    'order' => 'asc',
    'orderby'    => 'meta_value_num',
    'meta_query' => array(
      array(
        'key'     => 'concert_date',
        'value'   => $currentdate,
        'compare' => '>=',
      ),
    ),
  );
  $cpt_query = new WP_Query($args);
?>
<?php if ($cpt_query->have_posts()) : while ($cpt_query->have_posts()) : $cpt_query->the_post(); ?>

  <?php
    global $post;
    $date = get_field( 'concert_date' , $post->ID, false);
    // make date object
    $date = new DateTime($date);
  ?>
  <div class="shows-list">
    <?php the_title(); ?> <span>- <?php echo $date->format( 'n/d' ); ?></span>
  </div> <!-- /shows-list -->

<?php endwhile; endif; // end of CPT loop ?>
<?php wp_reset_postdata(); ?>
</div>