your plant will show sex when you start too flower it. when you flip the lights or natural light hits the 12 hr light 12 hr dark period. around august/late october. this is when plants would normaly start flowering too what i understand.
small pear shaped pod with small white hairs = female
some pics would help mate...
switch photo period to 12/12 to determin what it is (male/female) usually takes 7-14days to show sex though...hope this helps
sorry to inform you but that isnt always the case my friend,(however i know what you are talking about) i have just germinated 2 kali mist(6weeks ago) and the tallest fastest growing one was female,while the shorter stockier plant was male(needless to say he is dead now...lol)