I might have done something dumb

Ok so i grew the plants out about a month then i decided I was going to put them on 12/12 to pick out the genders. But about 5 days later someone told me that was going to make the whole start to end time an extra 3 weeks. so after 5 days i switched them back to 18/6 they didn't show any signs of sex yet. They have now been back on 18/6 about 2 weeks and its like they are budding at the tops anyways. on 3 of them there are little white hairs poking out towards the top of the plant and on 2 there are a bunch of ball type ones... but they look like they might open up into leaves but there are to many of them. Anyways I can pick out the 2 males now right? My real question is how is this going to effect my grow?

it may have a minor effect on yeild. but i hear about people doing that all the time. putting them into flower to sex them, then put them back in veg light cycle. it seems to work for some people, but i prefer to sex them in veg. and i much prefer to take cuttings off my known females so i dont have to waste time and resources feeding and taking care of a plant im gonna kill.

Two ideas:

1) Take a cutting, root it and do the 12/12 to find sex.

2) take a couple cuttings. Once rooted, toss the mother/poppa plant in 12/12 for sexing.

With #2, if it s male, nothing lost, kill it off (or save the pollen) And if is a female, you are already on the way to making buds with the clones waiting in the wings for second round.