At submission, if not before, take a little time to sketch a simple plan for getting ready for the viva.
When will you start? What do you need to do? Who do you need to ask for support?
As you ask and reflect on these questions you’ll realise changes or missing details. If you have a big thesis maybe you need to start reading it sooner. If you need more practise then you can make better arrangements with your supervisor or friends.
Sketch a plan, because it will help you to get organised – you can always make changes to it too! It can be hard to simply react if things change when your whole plan for prep is “just wing it”.
Good viva prep starts with a plan: you know what you need to do, when you need to do it and who will be there supporting you.