Male or female?

Hey guys....
Going good a couple weeks into my first dwc. I'm looking for a couple pointers/tips/ideas on the best way to find out whether I've got males or females. Do I have to be ready to flower and continue with 12/12....or can I find out the sex....then continue to veg on 18/6? I'm running 600W MH for veg...then switching to 600W HPS for flower. Any suggestions are appreciated!

You can go 12/12, sex them and then go back to 18/6. I would probably ease back into 18/6 though. Like a day of 14/10, then a day of 16/8, then right back to 18/6.

If they start to look like these.....Kil 'em!!

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a lot of plants right around the 6th week or so will show sex if you know what to look for, otherwise you need to put em in 12 12 for about a week and they will show, then you can get rid of the mnales and veg the girls. it is not a big deal to flower then revert back to 18/6 and veg again...any pictures? i could maybe tell by some pics....look right where the leafs stem, meets the branch and stalk of the plant. right in the crevase will either be a sack hanging off a pole or a tear drop shaped sack with 2 white hairs sticking out....you want the sack with the hairw. when they come it will be very obvious.

Thanks so much for the help!...Keep it comin!