A Month To Prepare
I don’t advise every PhD candidate take a month to get ready for their viva but a month is a good place to start from when considering your plans.
Viva prep – the deliberate tasks someone does to get ready for their viva – takes between 20 and 30 hours for most candidates. Viva prep includes activities like reading your thesis, rehearsing for the viva, annotating and making notes, checking papers and any other practical task you can think of that might help.
Taking a month for viva prep means that 20 to 30 hours breaks down to half an hour or an hour most days. You might take days off, you might do more each day in the final week, but there is a lot of time to spread things out. There is space to change plans. There is wiggle room in case anything goes wrong.
Some people thrive with the pressure of a tighter deadline. Two weeks can be enough time to get ready for your viva, but with two weeks you are committing to one or two hours every day and there is less margin for error.
For your viva and your viva prep you have to decide what is best for you. I would recommend starting with a month, sketching out a plan taking into account your other responsibilities, then see how that feels.