Hi there, this is Kitt. I have been told by my Doctor that 4-6 weeks is the average for the medication to kick in completely and this is for most of the ADs. It also will depend on how your body handles the medication.
You won't notice a sudden cure from any of the meds as there is no miracle pill but working together with you physician/therapist the medication should help you. this is my 2 cents worth. :)
I do not take this med but do use the Cymbalta.
Take care and keep posting.