There are a couple of ways you can go about rehearsing for your webinar Session before the webinar start date/time.
1) Copying/Duplicating the Event
The best option to test everything out before the Event – i.e. go live to start the recording, share the Video Materials, Presentation, Handouts, Polls or Featured Actions, etc. – is to copy/duplicate the event. This will duplicate the exact Event with all the Resources, Presentation Materials, Handouts, Polls, etc.
You can create a test Session in the duplicated Event and run it without Attendees. Once you are done testing the duplicate Event, you can archive/delete it.
2) Create another Session for the main Event
You can test out the Event, but instead of joining the main webinar Session, you can create another session under the same event for an earlier date and time.
Once you've tested everything out, you can cancel the test session.
Note: When you add a test Session to the main Event, the Session will appear on the Registration page and potential Registrants will be able to sign up for the test Session.