First, you might want to check out the
naming policy page and change your user name - if one of the sheriffs or bartenders hasn't said something to you yet, they're bound to in short order.
To answer your question, it depends. I took about three weeks to study for it, dedicating about three-four hours a night, but that's due to using
J2EE 1.3 at the office (the exam is based on J2EE 1.2) and wanting to be certain that I knew the difference between the technologies so I wouldn't trip myself up. It depends on how well you know the subjects.
And, before you fret, you can use
Java EE 5 on the Part II assignment. Part I hasn't been updated recently.