<?php

// create date object
$date = new DateTime( '2018-07-23 06:12:04' );

// get the queued event by ID
$event = \AutomateWoo\Queued_Event_Factory::get( $event_id );
$event->set_date_due( $date );
$event->save();

// alternatively you can get the event via a query 
$query = new AutomateWoo\Queue_Query();
$query->where_order( 1234 );

foreach ( $query->get_results() as $event ) {
	$event->set_date_due( $date );
	$event->save();
}