How long does it take to get the final result of a submentoplasty? (Photo)

I had a lower face lift, neck lift and submentaplasty just shy of six months ago. I went to a very reputable, double-board-certified surgeon in Manhattan. I love the results except for the bands that still hang down from my neck. My PS says the muscle is still contracting, and that it will be nine months before I see more improvement (the bands will be much less noticeable). Does nine months sound "normal" for a final result? I would appreciate any feedback.