actually the 1st day of flowering is when you see pistil clusters, i.e...more than 2 pistils. if you veg long enough a plant will show pre-sex pistils. this doesn't mean you start counting. introducing 12/12 activates a hormone that triggers the plant to flower. still not counting yet...usually in 3-14 days (depending on maturity) you'll see more than 2 pistils forming on top. once that happens, you can start counting. another thing about the countdown....they aren't set in stone. basic (very basic and general) guidelines in perfect conditions. most plants nowadays are hybrids, that being said, you may get a sativa dom. or an indica dom. ind.'s can flower up to 80 days, or only take 45 and anywhere in between. sativa's can go 90 or as low as 70, it just depends. this is where your scope comes in handy. it's the on,y real way to determine when to pull, or go another 2 weeks.