wow thats strange. i also have plants that are 7 and a half weeks into flowering right now xD I would say anywhere from 8.5-9 weeks should be good but if you have a microscope you can check the trics to confirm they are ready...
Up to you when you want to harvest. they are close to being done but i would probably wait the full 9 just to squeeze every last bit of crystal out of them that you can. Good luck hope you have a good harvest