I've been switching over Effexor XR for 2 weeks, slowly increasing the dose.

With my old SSRIs (Paxil, then Celexa), I noticed a sharp decrease in anxiety within a couple of days of increasing the dose. I'm not getting this at all with Effexor. I'm not getting worse, but I'm not getting better either. I know the packages say it takes 4-6 weeks, but shouldn't I feel something by now?