This counting of days that many seem to rely on is 100% worthless in determining when harvest is near,throw the calander away,there are way too many variable conditions in a grow to ever use day count to determine harvest windows.
You need to keep an eye on the trichomes,once they start turning a milky off white harvest is getting close,within a week to 2 weeks from when milky trichomes appear some will start turning a light honey color,once approx 50% of the trichome heads have turned honey or golden in color then you chop,this will give you the ultimate heavy couch lock knock out buzz,if you want a lighter buzz then harvest when only about 10% of the trtichomes are honey colored.
I grow a strain that is supposed to be able to be harvested in 44 days which is complete bullshit,i start my day count from when pistils first appear on a plant not from the 1st day i put them on 12/12 lighting,even with the more accurate day count ive never had any crop be ready in 44 days.
If you want your buds to be the hardest hitting smoke they can be you'll get a $30 microscope & harvest by trichome color,which on most indica dominate strains ive grown takes about 70 to 80 days from the first day of 12/12.