A list and two questions could be a simple way to manage your viva prep.
What do I need to do? How can I be sure I’ve done enough?
For the first question: look at what others tell you might help, compare it to where you feel there are gaps in your knowledge or confidence, and then make a list of what needs to be done as a result.
Assuming you’ve done enough simple work for your list, responding to the second question is straight-forward: when something gets done, cross it out. Move on to another task and as you see fewer and fewer things on the list you know you are closer and closer to being ready.
Lots of questions that explore viva prep can help – when to start, how much to do, when to do it and so on. These questions are valuable, but first explore what you need to do. What kinds of work will help you get ready?
Make a list, then work towards crossing it out.