It isn't that easy, but in the end, you'll see that it was worth it. In fact, the best certifications are
SCJD and
SCEA, because you have to practically deal with design and development.
Note that the programmer certification certifies that you understand the
Java language itself, but yet, a person that has this certification may not know how to use the language to solve a problem of the real world. It depends on how much time you can spend on the development, your understanding of the project and your experience with design, but in your case, I guess around 6 months. It's hard to say, but I guess it is something around it.
Cheers, Roberto Perillo
SCJP, SCWCD, SCJD, SCBCD