for anyone who is ready for the exam and afraid or don't have much confidence (like i was ); don't worry. the exam is pretty much easier than any mock exam.
i could finish all questions in about 1.5 hour
about my exam preparation; actually it took me 8 months to appear for the exam this is because of work and family but later i realized that this period could be reduced to 4 or even 2 months.
anyway i read K&B book about 3 times and solved many mock exams (K&B Practice Exams, Examlab and some exams from scjp mock tests page : https://coderanch.com/how-to/java/ScjpMockTests).
The level of the real exam is much easier than any of the mock exams.
The last thing : pay more attention to self test questions (after each chapter) in K&B book.