@Growmore short answer atleast 2 more weeks but the easiest way you can judge your plants maturity at home
is to use a handheld magnifier like jewellers use about 30x magnification should be ok.
Now you want to study the buds looking at the trichome glands. What you are aiming for is the triches to have changed from clear to clouded with atleast 20% of them progressed to an amber colour. Once you are at this stage you are very close to the optimum harvest time so once you are at that stage i would do a flush then leave the girls in the dark for 24 hour before the finalchop I hope this answers the question and I would to congratulate you on a job well done those plants look great