It helps to check a few final things before your viva.
Do you have your thesis?
Do you have a notebook and pen?
Do you have something to drink?
Do you have a few weeks of prep in your recent history?
Do you have everything else you need for the venue for your viva, whether that’s a seminar room or your home?
Do you have years of effort, experience and success bound up in your PhD journey?
If you can answer yes to all of these then you’re in good shape for meeting your examiners!