I finally passed the OCP
Java 8 exam. I spent around 4 months studying about 3 to 4 hours a day. I used the book "OCP: Oracle Certified Professional Java SE 8 Programmer II Study Guide: Exam 1Z0-809". I also practiced with the mock exams from enthuware.com.
My score on the OCA was 92% and on the OCP was 83%. The OCP was much harder. I actually though I had scored in the low 70's so was happy with my score.
Not sure of any specific advice I can give to others preparing for the
test. Lots of questions included Java 8 streams, but often were testing something else. The mock exams were very helpful. I think my average score on the enthuware mock exams was around 70%.