Hey Daniel,
Thanks for reaching out.
If by “new order e-mail” you mean an email sent by WooCommerce itself, then your best bet is to head over to the WooCommerce documentation to a page like this one → https://docs.woothemes.com/document/template-structure/
You can modify the HTML templates there to include the date where you’d like.
If you mean the tickets emails themselves, however, then instead head over to this page of our own documentation: https://theeventscalendar.com/knowledgebase/themers-guide/
To make the customizations, you’d apply the information in the above article to this file inside the Event Tickets plugin:
event-tickets/src/views/tickets/email.php
I’m sorry that our ability to help with customizations is so limited; but I hope this information helps you at least get started on things! 🙂
Cheers,
George