Wordress: Using custom fields as key to sort queries with meta_query and meta_key

$args['post_type'] = array('ur_post', 
    'programs_post', 
    'education_post', 
    'blog_post'
);
$args['meta_key'] = 'Start Date';
$args['meta_query'] = array(
    array(
        'key' => 'Start Date',
        'value' => date('Ymd'),
        'compare' => '>=',
        'type' => 'date'
    )
);
 
/*This will sort. Make sure there is no underscore. It's orderby NOT order_by.*/
$args['orderby'] = 'meta_value'; 
 
$args['order'] = 'asc';
$the_query = new WP_Query($args);
 
while ( $the_query->have_posts() ) {
    $the_query->the_post(); 
    $start_date = get_post_custom_values('Start Date', $the_query->ID);
 
    /*var_dump($custom_values);*/    
    if (date('Ymd',strtotime($start_date[0])) >= date('Ymd')) {     
        echo '<div class="event_date">';
        //display date here...
        echo '</div>';
 
        echo '<div class="event_post_time">';
        $start_time = get_post_custom_values('Start Time', $the_query->ID);
        echo $start_time[0];
        $end_time = get_post_custom_values('End Time', $the_query->ID);
        if ($end_time != NULL) {
            echo ' - '.$end_time[0];
        }
        echo '</div>';
    }
}
wp_reset_postdata();