imported post
Here's the best link I've seen:
http://www.stratfordnj.org/pdf/Firearms_instruction.pdf
It describes all of the paperwork you need, including the latest tax (SBI 212A) NJ has tacked on, with links to pdf's you can fill out online.
It will depend on where you live. A guy I work with just got his FID, lives in Fair Lawn, and it only took him 2 months. I've known others to take 8 months. NJ has a statute that requires it be given in 30 days, but I've never seen them NOT break their own law.
There's a gentlemen from Gun Owners of New Jersey who has listed his phone #, in order to call him if your town requires more than the described paperwork. Apparently a lawsuit was won that explicitly states that they can't require extra paperwork. I can't find the thread with his info. If I do, I'll post it later.