<?php

defined( 'ABSPATH' ) or exit;

wp_clear_scheduled_hook( 'mc4wp_refresh_mailchimp_lists' );

$time_string = sprintf("tomorrow %d:%d%d am", rand(1,6), rand(0,5), rand(0, 9) );
wp_schedule_event( strtotime( $time_string ), 'daily', 'mc4wp_refresh_mailchimp_lists' );