I think a good rule of thumb when time planning for this cert is to plan to study a minimum of 2-4 weeks for Part I and to budget a minimum of 100 hours for Part II/III.
You might complete Part II in less than that, but more likely, you'll use more, especially if you like to tweak or have frequent interruptions (like going to work, vacations, life ). A reasonable range estimate would be 100-400 hours for Part II, depending on your knowledge of J2EE, previous experience, and dedicated blocks of time. While you can spend less time, you may overlook some critical requirements. If you spend more time, you need to recognize that it is time to stop and submit.
Hope this helps! I posted some notes in the SCEA forum.