Yo omg thank you so fucking much you're an angelTip: You can take a cutting from the unknown plant, stick it in a glass of water, and put it directly to a 12/12 light cycle.
It will show the sex before it even starts rooting out, and then you'll know way ahead of time so you don't waste time.
A good way to determine sex, without affecting the host plant in any way, keeping the momentum going...