It took me roughly 3 months to get a response from HR several years ago when I started my job search, that led to a great job at NG that I enjoy. Another couple months went by, and was eventually offered the job, that was apparently available at the time I first started the process. Can't tell you why it took 6 months after I started the process. If your in a hurry, and have inside contacts for the position your applying for, I'm sure it can go pretty quick.
I know there are managers in NG frustrated that if they interview someone, they often find the person found another job before NG HR was able to get offers out. Be Proactive!