I started in Sept. 07 and will be done with my top teeth in about 6- 8 more weeks and the bottom about 5 weeks after that. I noticed right away the movement in my upper teeth and have been tracking my progress with pictures. Only of late have I been having more discomfort in my jaw and some headaches, but the teeth are moving and from what I have heard about the old style metal braces is THAT is way more uncomfortable. I am happy with my decision to go with Invisalign.