I was about to say, "What's IBM-833"... didn't realize my 486 is obviously out of date.

I think that taking 833 is definitely a good idea, at least in terms of preparing for Part II.
Do you need five years of experience before sitting for this exam? No, of course not. Do I think it's a good idea? Certainly.... and you're the only one who can really judge if you are prepared or not for this examination. SCEA is not just a
test of how well you can design a system, but of your grasp on the
Java EE technologies and how they are applied in the design of a software system, and how well you can explain why you applied what portion where.
Best of luck!