i was always under the impression the stress was pretty bad, making some hermies in bad situations, nothing could happen but at the same time ever female could turn hermie. i would just leave them all until flowering and just do it normally. When u sex them u will have all the room they need for flowering. it should only take a week, and the plants grow the most in flower i wouldnt worry about the cramped space until then when they really need all the light they can get. maybe place the taller plants to the outside of the lights, organize the set up so that the males u might think are males will not shadow out some good females. Males are ussually taller, so if your growing a strain look for this. Although it could be wrong and some femals may be just as tall.