I just passed the SCJP 6 with a score of 90%. I must say that it was really easy after all the hours studying K & B's book, the Devaka's Exam Simulator, and reading this forum's posts. Oddly enough, I only answered wrong in the Flow Controls and Fundamentals categories.
many congratulations. I have started preparing and targeting May 3rd week for the exam. studying 1 to 2 hours during weekdays due to work and weekends 4 hours. hope this should be enough. I am working in Java for last 7 years.
Please comment if i need to do more. Also, Devaka questions are for SCJP 5.0 only? Though 6.0 version has slight changes only.