It depends on weather or not your planning on growing long term or not, but what I would do of I were u is, I would start training them (lst- low stress training). You do this by bending them over and tieing them down. This Weill give you better light to more bud sites. If u start doing this now u will be able to keep them in the veg room longer. This will make u be able to wait for them to show sex. I don't like to flower my plants grow from seed until they show preflowers. Once they show preflowers, u will k ow what u got for females or males. If u got at least one female, u can then take a few clones and send the big one or two int flower. And let the clones veg and turn one or both into mother plants that h can take as many cuttings u need to fill up your big tent.
Now about your tent, 76x76x76 is a good size tent, but I think u said u have a 250w hps? Thang s not going to cut it. It will be fine if u just want to grow the one or two u got, but more than that will be tough. I would invest in one or two 600w cool tubes, two would be ideal, but it can be tough shelling out that much loot. You would the need an exhaust fan to cool the light/lights.
I'm not trying to overwhelm u, but it can get pricey. The way I look at it is, if your going to be using two rooms, one of which being that big, u might as well fill them up with big buds! I'll help u out, as well as everyone else here I'm sure, so don't sweat it. Your plants are looking great so far by the way, your already off to a good start. Hope this helps!!