Reminder email

I tried setting up a simple reminder email (by starting wp-cron) but it didn’t work. Is there another solution?

// === REMINDER ===
update_post_meta($booking_id, '_creavibc_reminder_sent', '0');

// === REMINDER FUNCTIONALITY ===
define(‘CREAVIBC_REMINDER_ENABLED’, true);

function creavibc_send_reminders() {
if (!CREAVIBC_REMINDER_ENABLED) return;

global $wpdb;
$now = current_time('mysql');
$reminder_threshold = date('Y-m-d H:i:s', strtotime('+24 hours'));

$bookings = $wpdb->get_results("
    SELECT p.ID, 
           pm_date.meta_value as booking_date,
           pm_time.meta_value as booking_time,
           pm_name.meta_value as customer_name,
           pm_email.meta_value as customer_email,
           pm_service.meta_value as service_id
    FROM {$wpdb->posts} p 
    LEFT JOIN {$wpdb->postmeta} pm_date ON p.ID = pm_date.post_id AND pm_date.meta_key = '_creavibc_booking_date'
    LEFT JOIN {$wpdb->postmeta} pm_time ON p.ID = pm_time.post_id AND pm_time.meta_key = '_creavibc_booking_time'
    LEFT JOIN {$wpdb->postmeta} pm_name ON p.ID = pm_name.post_id AND pm_name.meta_key = '_creavibc_booking_name'
    LEFT JOIN {$wpdb->postmeta} pm_email ON p.ID = pm_email.post_id AND pm_email.meta_key = '_creavibc_booking_email'
    LEFT JOIN {$wpdb->postmeta} pm_service ON p.ID = pm_service.post_id AND pm_service.meta_key = '_creavibc_service_id'
    LEFT JOIN {$wpdb->postmeta} pm_reminder_sent ON p.ID = pm_reminder_sent.post_id AND pm_reminder_sent.meta_key = '_creavibc_reminder_sent'
    WHERE p.post_type = 'creavibc_booking' 
    AND p.post_status = 'publish'
    AND CONCAT(pm_date.meta_value, ' ', pm_time.meta_value) BETWEEN '$now' AND '$reminder_threshold'
    AND (pm_reminder_sent.meta_value IS NULL OR pm_reminder_sent.meta_value = '0')
");

foreach ($bookings as $booking) {
    $service_title = get_the_title($booking->service_id);
    $subject = "[REMINDER] " . $service_title . " - Appointment Tomorrow";
    $message = "Hi " . $booking->customer_name . ",\n\nThis is a reminder for your " . $service_title . " appointment tomorrow at " . $booking->booking_time . ".\n\nSee you soon!";

    wp_mail($booking->customer_email, $subject, $message);
    update_post_meta($booking->ID, '_creavibc_reminder_sent', '1');
}

}

if (CREAVIBC_REMINDER_ENABLED) {
add_action(‘creavibc_daily_reminder_cron’, ‘creavibc_send_reminders’);
if (!wp_next_scheduled(‘creavibc_daily_reminder_cron’)) {
wp_schedule_event(time(), ‘daily’, ‘creavibc_daily_reminder_cron’);
}
}