2 weeks minimum to have an effect -- that is, see some little improvement. It may be 6-8 weeks before it begins to work, and by that I mean you begin to see improvement but you're not complete yet. It could take 8-12 weeks to get the med at 100%. ALSO, it can take more time if the dose must be increased, you should 'reset' the time table after every increase, although I think it should take a little less time to get the full effect.

I am not saying this to make you miserable and impatient, I am saying this because it is always best to give ADs their time. They are not an instant turn around, it takes time to mend your brain back from anxiety or depression.