Finally I've passed my OCPJP exam with 91% score. Preparation took me about 4 month of almost everyday study with full-time job.
I've created github repositories (for both OCAJP and OCPJP), so if someone is interested you can check what test programs I wrote and what edge cases I tested.
1. OCAJP github repo 2. OCPJP github repo
Roughly speaking I've thoroughly read books by Boyarsky J., Selikoff S. (big thanks to authors) and took Enthuware (a bit more difficult than real certification) tests.
This approach allowed me to pass OCAJP with 97% and OCPJP with 91%.
Big thanks to everyone who shared their experience, this helped me a lot also.
P.S. Just some notes about books I've mentioned: I had questions related to JDBC which weren't covered in book, consider reading some additional info about JDBC related topics (authors have mentioned this discrepancy somewhere on forums).
P.S.S. If someone is interested, I have about 7 month of real programmer experience with no format education background in this area.