Obviously, I am not a doctor, but I don't think Xanax is the best way to deal with day-to day generalized anxiety. That stuff makes me a zombie and I only use it once in a while when I am starting to have panic attacks to keep those at bay and get myself kind of "leveled off" again. Usually like one pill at night for a day or two.
You should definitely talk to your doctor about your TTC plans and maybe they can give you some options for managing your anxiety with a different drug or weaning you off of Xanax and seeing how it goes.
I would do this before you get pregnant because you shouldn't be going cold turkey off of any medication like that.