i wouldnt really count the hours from dusk to dawn, i mean just bc it's a bit light outside doesn necessarily mean you've got sunlight hitting them. if you got the seeds and they werent super expensive yea grow all of em. go ahead and grow them close so that they all get the same amount of light and will grow at the same rate, that as soon as they do start growing the sex organs, then you can pull the males out. have you thought about cloudy days? i mean, there's really not anywhere in the world that it's just beautiful everyday. if i had to guess, and from what ive read on this site, ppl start flowering as early as 6-8", that's not tall at all. so you can expect to see the sex very soon. just start growing and see what happens. i mean it takes all but a few seconds to see what sex they are once the pistils or seeds pods grow. also, the males do not pollinate the females immediately. i bet you have 1-3 days to get them outta there before they bust a nut on the females.