You could plot out minute by minute when you are going to do your viva preparations. When will you read Chapter 4? How will you make notes for various sections? Which colour highlighters will you use to encode different associations?
How far in advance will you bring up mock vivas with your supervisor, and how will you raise the topic? Which approaches will you follow for making summaries? How often will you re-read your thesis, and at what intervals? Who will you look to for advice, and when will you let them know what you need?
There are many, many questions you can ask yourself to figure out what you’ll do. Many plans you can set in motion. There’s always more detail you can pile on. And at the end of it all you could be a viva-ready machine, thoughts all composed just-so, almost every detail anticipated.
But do you need to do all of that? Is that really what you need?
Or rather than overcomplicate things, can you focus on the fact that you did the work, that it’s good, and that really viva preparation is just checking details, reflecting on your work and finding some opportunities to talk?