I just began my Invisalign treatment yesterday. I just learned that we would begin treatment with my bottom teeth first; the top set with not start UNTIL 41 months! That was not the original plan. Originally, they thought they were going to have to do an extraction of my bottom teeth to avoid an underbite. Then, it was decided by a dentist at Invisalign that it would not be necessary;however, waiting over 3 to treat my top teeth does not makes sense! It was supposed to be 3yrs together!!! :(