Zone 5 and my tomatoes are just starting to turn. Mostly I have yellow ones (the red ones didn't make it), first it was just one yellow one that I picked earlier this week, now all of a sudden I am seeing more, I have about 3 almost ready. I also have some red saladette (like Roma only smaller), with tons of green ones just waiting, slowly the first 5 turned red, and now they seem to be taking off. Like a PP said, I think in a few weeks I'll be wondering what I was worried about.
(If you are in a place that deals with early frost, I read somewhere to pinch off all of the growing tips a month before first frost so that the energy starts going into ripening instead of growing.)