How to use WordPress Cron to Schedule Events | http://www.ibenic.com/how-to-use-wordpress-cron-to-schedule-events

cron_schedule.php

<?php

add_filter( 'cron_schedules', 'six_hours_custom_schedule' );
 
function six_hours_custom_schedule( $schedules ) {
    $schedules['every_six_hours'] = array(
        'interval' => 6 * HOUR_IN_SECONDS,
        'display'  => esc_html__( 'Every Six Hours' ),
    );
 
    return $schedules;
}

schedule_events.php

<?php

add_action( 'publish_post', 'get_share_counts_for_post', 20, 2 );
/**
 * Schedule the share counts for this post 
 */
function get_share_counts_for_post( $post_id, $post  ) {
  
  // Getting a UNIX Timestamp
  $timestamp = get_post_time('U', false, $post);
  
  $args = array( $post_id );
  $hook = 'get_share_counts_every_six_hours';
  
  $scheduled_timestamp = wp_next_scheduled( $hook, $args );
  
  if( $scheduled_timestmap == false ) {
    wp_schedule_event( $timestamp, 'every_six_hours' $hook, $args );
  }
}

add_action( 'every_six_hours', 'update_share_counts_for_post' );
/**
 * Update the share counts for the post 
 */
function update_share_counts_for_post( $post_id ) {
  // Process the share counts
}

single_event.php

<?php

// You can use any custom post type in the hook such as: 'publish_book' for a custom post type of 'book'
add_action( 'publish_post', 'share_my_post_after_hour', 10, 2 );

/**
 * Getting the timestamp and applying 1 hour in seconds to it for scheduling
 * Scheduling a single event with the post ID
 */
function share_my_post_after_hour( $post_id, $post ){
  
  // Getting a UNIX Timestamp
  $timestamp = get_post_time('U', false, $post);
  
  // Using WordPress Time Constants
  // https://codex.wordpress.org/Easier_Expression_of_Time_Constants
  $timestamp_after_hour = $timestamp + 1 * HOUR_IN_SECONDS;
  
  // Define remaining parameters
  $args = array( $post_id );
  $hook = 'share_the_post_after_hour';
  
  // Get the timestmap of an already scheduled event for the same post and the same event action ($hook)
  // Returns false if it is not scheduled
  $scheduled_timestamp = wp_next_scheduled( $hook, $args );
  
  if( $scheduled_timestmap == false ) {
    wp_schedule_single_event( $timestamp_after_hour, $hook, $args );
  }
  
}

add_action( 'share_the_post_after_hour', 'process_sharing_for_post' );
/**
 * Processing the sharing for a post
 * @param numeric $post_id The ID passed through the hook in the $arg variable
 */
function process_sharing_for_post( $post_id ) {
  // Create the logic to share the post
}

unschedule_event.php

<?php

/**
 * Action that is called when a post has been moved to trash
 */
add_action( 'trashed_post', 'unschedule_sharing_from_post' );

/**
 * Unschedule the sharing event on a post
 */
function unschedule_sharing_from_post( $post_id ) {
  
  $args = array( $post_id );
  $hook = 'share_the_post_after_hour';
  
  $timestamp = wp_next_scheduled( $hook, $args );
  
  if( $timestamp ) {
    
    wp_unschedule_event( $timestamp, $hook, $args );

  }
}