Sort order by date.

Sortby-Date

/* My metabox array */
array(
  			'name' => 'Start Date',
				'desc' => 'Project Start Date',
				'id'   => 'startdate',
				'type' => 'text_date',
			),

/* My query function */
function mmi_projects_loop () {
  
	$args = array(
		'post_type' => 'projects', // enter your custom post type
		'meta_key' => 'startdate',
		'orderby' => 'meta_value_num', // used to determine the order of CPT displayed
		'order' => 'DESC',
		'posts_per_page'=> '-1',  // overrides posts per page in theme settings
	);