I toke some clones off of a 5-6 wk. flowering hybred and it worked out. The only problem I had was when I finally havested my "clone giver" she was sort of skanky. I crossed a blue cheeze with a NLx shiva male and it sucks. It looked good with decent yields but I didn't like the smoke. I cloned 6-7 cutting showing trichomes at the base of the plant and all but one survived. I just tossed them out yesterday which was hard to do but I got enough inventory to last me till my next grow. No use growing more inventory that I really don't like very much. Good luck, it can work.
Just be patient and leave em alone in their humidity chamber. You'll see little buds and trichomes but leave the lights on 20-24 hr. a day and eventually it will revert back to the veg stage.