Is 2 and a half days enough time to prepare for a viva?


Just received an email from my examiners offering me my viva defence in two and a half days' time. I had not started the preparation for my viva yet as was anticipating a much later date for it. For context I submitted my thesis some 3 months ago and although I feel I remember it I have not been able to devote the time to prepare for it. Do the 2.5 days give me enough time or should I ask my examiners if they are able to delay it a week?