Create a UNIX timestamp based on two meta fields

gistfile1.aw

<?php

/**
 * Create a UNIX timestamp based on two meta fields
 * @author Bill Erickson
 *
 * @uses text_date_timestamp (for date, UNIX)
 * @uses text_time (for time, XX:XX AM/PM)
 * @link https://github.com/jaredatch/Custom-Metaboxes-and-Fields-for-WordPress
 *
 * @param int $post_id
 */
function be_timestamp_meta( $post_id ) {

	// Limit to 'event' post type. You can put whatever limit you want here
	if( 'event' !== get_post_type( $post_id ) )
		return;
		
	$date = get_post_meta( $post_id, 'be_event_date', true );
	$time = get_post_meta( $post_id, 'be_event_time', true );
	if( !empty( $date ) && !empty( $time ) ) {
		$date = date( 'm/d/Y', $date );
		$timestamp = strtotime( $date . ' ' . $time );
		update_post_meta( $post_id, 'be_event_timestamp', $timestamp );		
	}
			
}	
add_action( 'save_post', 'be_timestamp_meta', 99 );