I took my Exam the past Monday April 18th. I was not feeling confident and questioned my readiness a few days prior as well. I had a thought of changing the date, but then realized what was the point, in prolonging this. I agree with Yasir and his comments. The best thing you can do for yourself is to be well rested for exam day. I only spent a few hours, the day before, reviewing notes and practicing my brain dumps. Shut it down early the day before relax and get a good nights rest.
Think positive, and Good Luck to YOU!!