It's early. Looks like it has some filling in to do yet and the hairs are still white. I have no experience with sativas, but I would guess another three or four weeks. Good looking plants, should be some excellent smoke!
I don't know what the climate is like there but I would ride it out as long as you can while not getting frost. Those cola's are not going to be cola's if you cut them now.
I agree with freda,