I searched, but don't know the right terms to search for. Let's say I start 10 seeds. When done vegging, start the 12/12 light, when males are revealed, remove them. Could I take one new female and return her to the 18 hour light schedule to keep her to clone from? Not for lack of trying....
Yes you can take a clone in the flowering stage..early or late. Your clone will re-veg and will be a much bushier plant than the mother. So it would be a good thing, not a bad thing. Here's a link about it. http://www.ilovegrowingmarijuana.com/monster-cropping-marijuana-plants/
You could also wait for a while until preflowers show up, then take your clones. That way you don't have to worry about freaking out your new clone with a new light cycle. Or take clones of every one, label them then toss out the male clones. Good luck blade!