Well, at least you have read through parts of it once. That's better than nothing.
At this stage:
- Don't try to finish reading the whole thing, but do have a look at anything you think the examiners will pick up on.
- Try to stay calm
- Focus on practical prep e.g. put post it note markers in your thesis at the start of chapters or by key tables/figures so you can find them quickly and don't get flustered in the viva
- Set out whatever you need for tomorrow (clothes, paperwork) so you don't have to rush in the morning.
- Get a good night's sleep
Good luck!