Preparation time for Java Certification
vary from person to person and it requires lot of dedication & hard-work.
Both the exam each takes around 2 months of time if you have little background on Java already. It also depends on how you are preparing for the exam. OCPJP is more tougher than OCAJP Exam. OCAJP can be cleared with out much in depth knowledge on Java programming but OCPJP covers lot of topics that requires some kind of practice.