// Custom Cron Recurrences
function custom_cron_job_recurrence( $schedules ) {
	$schedules['twentymin'] = array(
		'display' => __( 'Twenty Minutes', 'textdomain' ),
		'interval' => 1200, // time in seconds
	);
	return $schedules;
}
add_filter( 'cron_schedules', 'custom_cron_job_custom_recurrence' );

// Schedule Cron Job Event
function custom_cron_job() {
	if ( ! wp_next_scheduled( '' ) ) {
		wp_schedule_event( time(), 'twentymin', 'getupdates' );
	}
}
add_action( 'wp', 'custom_cron_job' );