A simple plea for a Saturday: always, always read the regulations for thesis examination at your institution. Read the rules for the viva at your university.
They might be a little dull in places, but you will get confirmation about who does what, when you find things out and see estimates on how long things like the submission period will take.
There may even be things you don’t expect: a candidate told me recently that they had to take proof of their identity to their viva!
Always check the rules. It won’t take much to find them and won’t take long to read them.