Hi Jones,
SCJD is an assignment, not an exam with multiple choice questions like the scjp one. Being a scjd shows that you are a decent
java developer: making good design decisions, writing fine javadoc comments and user manual,... It doesn't proof that you have knowledge about any particular topic. It will give you great insight in threading and making your program thread-safe, a little bit about fui development (swing and awt) and rmi (or sockets).
So if you want to use it for job opportunities, you will go for a more specific certification like the scwcd or scbcd or both

Certainly if you have to combine it with a fulltime job, because it is hard to combine scjd with a fulltime job and a social life. But if you now have some free time (2 weeks, 1 month,...) maybe you could do the scjd and give full attention to it in your free time, so you can finish it in your free time. And after you have submitted it, you will have to wait 4-6 weeks for your grade. And that time you could use to do the scwcd or scbcd.
[edit]The reference for the SCJD is definitely
the book of Andrew Monkhouse. Regarding the SCWCD it seems the HFSJ is
the reference for that certification
Kind regards,
Roel