I'm changing my medication from Effexor (venlafaxine) 300mgs to wellbutrin 150mgs. How long before I notice a change in my mood?

Many Variables. When switching from one antidepressant to another it is difficult to predict how quickly the new medication will take effect. Generally one expects an antidepressant to begin to work after two weeks with the maximum benefit at six weeks. One should taper slowly off Effexor (venlafaxine) due to discontinuation symptoms. These would include anxiety and flu-like aches and pains. Work closely with your md.