i reveg plants all the time and they dont go hermie, growers do go 12-12 then find out the sex and flip back to veg so it is possible to do and it dont cause hermies, i reveg several clones and at least 1 plant per grow and thats stressing the plants a lot more than letting them go 12-12 to show sex then flipping back to veg, ive never had problems with hermie plants so i think a reveg would cause a lot more stress than going 12-12 to show sex then flipping back to veg, look at the crazy leaf growth you get with a reveg plant, so the stress is much higher for a reveg,
the clone method is a good option but a plant will only show sex when its mature enough, so the clone may not be far off the mother plant showing sex, even going 12-12 form seed dont really speed things up as my 12-12 from seed plants show sex at roughly the same time as the plants in veg do, i know 24-0 takes much longer to show sex followed by 20-4, but 18-6 seems to show sex pretty quick and usually around week 6 of growth depending on strain, glr is the fastest light schedule to show sex and i find its the best veg schedule to use, but while im growing autos i cant use glr but will be using it possibly after these autos i got growing now have finished.
so i dont think you will save much time by taking a clone and putting that 12-12 unless your planning on a long veg under 24-0, if your using 18-6 then the plants will mature as normal and you will then be able to tell sex, all the plants ive got growing now was flipped to 12-12 about 3 days ago now and all have been showing sex for a while, so under 18-6 id say they would start showing sex around week 6 but some sativas tend to take a bit longer to show sex, at least thats what im finding with the strains ive been growing, but mots plants i grow show sex around week 6 onwards, it usually works out to the plant been about 1ft high but again depends on strain.
the only hermies ive got is when i want to hermie a plant so leave it in flower for 3 weeks longer than it needs to be, but thats just to get some fem pollen for fem seeds, none of my reveg plants have ever turned hermie and the last reveg plant i harvested had been harvested 3 times in total, it had been reveg twice, so that lasted me 3 whole grows and didnt have any signs of hermie even before i harvested it last time, in fact ive got a clone from that in reveg now.
but go with what you thinks best, a lot of people reveg plants and dont have problems with them turning hermie, we wouldnt reveg if we risked growing hermie plants, at least i know i wouldnt, but so far its all been good,