Run these workers from cron at sensible intervals.

Example cron entries:

*/5 * * * * /usr/local/bin/php /home/USERNAME/public_html/sunsetplanner/workers/send_email_queue.php >> /home/USERNAME/logs/sunsetplanner_email_worker.log 2>&1
*/5 * * * * /usr/local/bin/php /home/USERNAME/public_html/sunsetplanner/workers/send_sms_queue.php >> /home/USERNAME/logs/sunsetplanner_sms_worker.log 2>&1
*/10 * * * * /usr/local/bin/php /home/USERNAME/public_html/sunsetplanner/workers/run_notification_plans.php >> /home/USERNAME/logs/sunsetplanner_notification_worker.log 2>&1

Adjust paths for your hosting environment.
Start with stub transports first.
After confirming queue flow works, switch site settings:
- mail_transport = php_mail
- sms_transport = stub or future provider