When it’s time to prepare for your viva, show that you’ve thought about what you need from your supervisors. If you want a mock viva, ask as far in advance as possible. If there are particular areas you would like feedback on, figure out questions that will help focus your supervisors. If you want to know what it’s like to be an examiner or get a different perspective then tell them.
You know by now that your supervisors can offer a lot of help due to their knowledge and experience. So be thoughtful and targeted with your requests – thoughtful so that they get as much notice as possible of your needs, targeted so that you stand the best chance of having those needs met.
Your supervisors’ time is valuable. Treat it that way.