Order posts by post meta dates: Storing dates in post meta enables easy grouping of posts into current, future and past. This automatic grouping simplifies the client workflow and helps site visitors. https://www.damiencarbery.com/2018/12/order-posts-by-post-meta-dates/

course-dates-cmb2.php

<?php
/*
Plugin Name: Order posts by post meta dates
Plugin URI: https://www.damiencarbery.com/2018/12/order-posts-by-post-meta-dates/
Description: Storing dates in post meta enables easy grouping of posts into current, future and past. This automatic grouping simplifies the client workflow and helps site visitors.
Author: Damien Carbery
Version: 0.2
*/


// Allow entering start and end dates for Family Focus and Tailored Training training sessions.
// This will allow ordering of posts and sorting into current/forthcoming/past.
add_action( 'cmb2_admin_init', 'cad_training_dates_metaboxes' );
function cad_training_dates_metaboxes() {
	$cmb = new_cmb2_box( array(
		'id'            => 'cad_training_dates',
		'title'         => 'Training Dates',
		'object_types'  => array( 'post', ), // Post type
		'context'       => 'normal',
		'priority'      => 'high',
		'show_names'    => true, // Show field names on the left
	) );
	$cmb->add_field( array(
		'name' => 'Enter start and end dates',  // This is not needed here.
		'desc' => 'Complete this section for "Family Focus" and "Tailored Training" posts. Ignore it for other posts.',
		'type' => 'title',
		'id'   => 'training_dates_title'
	) );
	$cmb->add_field( array(
		'name'        => 'Start Date',
		'desc'        => 'What date does this training start?',
		'id'          => 'training_start',
		'type'        => 'text_date_timestamp',
		'date_format' => 'j M Y',
	) );
	$cmb->add_field( array(
		'name'        => 'End Date',
		'desc'        => 'What date does this training end?',
		'id'          => 'training_end',
		'type'        => 'text_date_timestamp',
		'date_format' => 'j M Y',
	) );
}


// Verify that CMB2 plugin is active.
add_action( 'admin_notices', 'verify_cmb2_active' );
function verify_cmb2_active() {
	if ( ! defined( 'CMB2_LOADED' ) ) {
		$plugin_data = get_plugin_data( __FILE__ );
		$plugin_name = $plugin_data['Name'];
?>
<div class="notice notice-warning is-dismissible"><p>Plugin <strong><?php echo $plugin_name; ?></strong> requires <a href="https://wordpress.org/plugins/cmb2/">CMB2 plugin</a>.</p></div>
<?php
		//error_log( 'CMB2 is not active.' );
	}
}

course-dates-on-single-post.php

<?php
// Display the start and end dates of a Family Focus or Tailored Training course at the top of the post.
add_action( 'genesis_entry_content', 'cad_course_dates_on_single_post', 5 );
function cad_course_dates_on_single_post() {
	if ( ! is_single() ) {
		return;
	}
	
	global $post;
	$start_date = get_post_meta( get_the_ID(), 'training_start', true );
	$end_date = get_post_meta( get_the_ID(), 'training_end', true );
	
	if ( ! empty( $start_date ) && ! empty( $end_date ) ) {
		echo '<p>Start date: ', date( 'l j M Y', $start_date );
		echo '<br />End date: ', date( 'l j M Y', $end_date ), '</p>';
	}
}

sort-courses.php

<?php
// Sort Family Focus and Tailored Training courses into Current/Forthcoming/Past.
add_shortcode( 'training-schedule', 'cad_training_courses_posts' );
function cad_training_courses_posts( $atts, $content, $code ) {
	$atts = shortcode_atts( array(
      'category'   => '',
      'image_size' => 'medium',
      ), $atts );
	// A category must be specified.
	if ( empty( sanitize_text_field( $atts[ 'category' ] ) ) ) {
		return '';
	}
	
	$now = time();
	$category = sanitize_text_field( $atts[ 'category' ] );
	$image_size = sanitize_key( $atts[ 'image_size' ] );

	$current_courses = array();
	$forthcoming_courses = array();
	$past_courses = array();

	$args = array( 'post_type' => 'post', 'category_name' => $category, 'posts_per_page' => -1 );
	$q = new WP_Query( $args );

	if ( $q->have_posts() ) {
		while ( $q->have_posts() ) {
			$q->the_post();
			global $post;
			
			$permalink = get_permalink();
			$title = $title = '<a class="title" href="' . apply_filters( 'the_permalink', $permalink ) . '">' . apply_filters( 'the_title', get_the_title() ) . '</a>';;
			$image = '';
			if ( $image_size && has_post_thumbnail() ) {
				$image = '<a class="image" href="' . $permalink . '">' . get_the_post_thumbnail( $post->ID, $image_size ) . '</a> ';
			}
		
			$start_date = get_post_meta( get_the_ID(), 'training_start', true );
			$end_date = get_post_meta( get_the_ID(), 'training_end', true );
			// Set a default as some posts may not have set the start and end dates.
			if ( empty( $start_date ) ) {
				$start_date = 0;
			}
			if ( empty( $end_date ) ) {
				$end_date = 0;
			}
			
			$course_markup = '<div class="listing-item">' . $image . $title;
			// Determine whether the course is past, ongoing (current) or future (forthcoming).
			// Include the date if it was stored in post meta.
			if ( $now < $start_date ) {
				if ( $start_date > 0 && $end_date > 0 ) {
					$forthcoming_courses[] = $course_markup . sprintf( '<p>Runs: %s until %s</p>', date( 'l j M Y', $start_date ), date( 'l j M Y', $end_date ) ) .'</div>';
				}
				else {
					$forthcoming_courses[] = $course_markup .'</div>';
				}
			}
			else {
				if ( $now < $end_date ) {
					if ( $start_date > 0 && $end_date > 0 ) {
						$current_courses[] = $course_markup . sprintf( '<p>Started: %s,<br />ends %s</p>', date( 'l j M Y', $start_date ), date( 'l j M Y', $end_date ) ) .'</div>';
					}
					else {
						$current_courses[] = $course_markup .'</div>';
					}
				}
				else {
					if ( $start_date > 0 && $end_date > 0 ) {
						$past_courses[] = $course_markup . sprintf( '<p>Ran: %s until %s</p>', date( 'l j M Y', $start_date ), date( 'l j M Y', $end_date ) ) .'</div>';
					}
					else {
						$past_courses[] = $course_markup .'</div>';
					}
				}
			}
		}
		wp_reset_postdata();
		
		$courses_markup = '';
		if ( ! empty( $current_courses ) ) {
			$courses_markup .= '<h3 class="course_header">Current Courses</h3><div class="display-posts-listing">' . join( '', $current_courses ) . '</div>';
		}
		if ( ! empty( $forthcoming_courses ) ) {
			$courses_markup .= '<h3 class="course_header">Forthcoming Courses</h3><div class="display-posts-listing">' . join( '', $forthcoming_courses ) . '</div>';
		}
		if ( ! empty( $past_courses ) ) {
			$courses_markup .= '<h3 class="course_header">Past Courses</h3><div class="display-posts-listing">' . join( '', $past_courses ) . '</div>';
		}
		
		return $courses_markup;
	}
	else {
		return '';
	}
}