I noted last year that the tomatoes really started ripening after I picked the first green ones off before a frost warning. This year I started pinching off the suckers at the first of August. Yesterday I picked the first green tomatoes, just one of the bigger tomatoes from each of the bigger plants. I noticed I already have one tomato (still on the plant) that's starting to turn orange.
These will sit in the window on the plant stand and hopefully ripen slowly, while giving the plants the message to mature the tomatoes still out on the plants.