I had 21 sessions in the fall. It did not start working until around the 13th session. Then it worked beautifully and has kept working. For me it's basically the only thing I respond to when in a deep depression/mixed state.

Are you having unilateral or bilateral? Unilateral does not work for me. Bilateral is worse for my memory but it works. Honestly if you are not feeling even slightly better by the seventeenth session, I would stop treatment. I don't think the side effects and Possible brain damage are worth it if it's not working. I'm willing to take it because it works so well but if it didn't I would have bailed.