Hi, Most doctors say anywhere from 4 to 6 weeks, but it can take longer. there alot of posts that can possibly help you find out more about Effexor on this site. I wish I had more information, because this drug didn't do anything for me, but make my situation worse. I don't and never have suffered from depression, Effexor enhanced my anxiety levels and brought on depression, my doctor took me off ASAP. I really hope it works for you, but if you read some other posts, you will see what I am talking about.
I am not a doc, so taking advice from me, would not be smart..

I didn't care for it, and would not recommend it, solely for the fact, you have been on it for quite some time, and it seems it is not doing it's thing. But that sometimes happens when you increase your dosage, seems like you have to start all over again on the time frame.
Good luck and hang in there, posting helps!
Ariom