It took about 11 months in my B1/B2 case. After waiting 3 months I asked them to send my passport back which they did immediately as I had a trip abroad. Upon return I kept calling U.S. center every two weeks and the lady would always say, it's in Administrative Processing Sir. Then one good day someone from Embassy called me and said I should deliver my Passport to AMEX as the visa processing is complete. I got it after 4 days. 5 Years Multiple.
My advice is just FORGET that you ever applied visa. Wash it from you memory. And it will speed up 
There is no use of calling them.