You can register/edit the streaming URL for your event at any time. 

If you haven’t created the streaming URL when publishing the event page, you can still add the URL later through the Edit event page. In that case, please let the attendees know beforehand the date and time you're planning to add the streaming URL in the event instructions (e.g., "Streaming URL will be added 1 hour before the start of the live stream"). The attendees will be able to access the Watch Stream page immediately after ordering a ticket, so it is important that you inform them promptly about when the streaming URL will be available.

When you are ready to add the streaming URL, please go to the Edit event page.

Locate "Online Event Settings" and click "Edit Settings".

Finally, enter your streaming URL and update the event instructions if applicable. Please click "Save".