Ok,
You should have topped during veg as everyone else has said. (i have my veg system into 3 part, so i top/prune during the end of the 1st or very begining of the second period so they have time to recover and actually grow the cola stems)
Nothing extraordinary will happen now, you will just have one cola. The basic theory (and I have found this to be most true) that its all dependant on the strain, some will have almost like a cap on what she will produce, so sometimes two colas will be best sometimes topping will give you two smaller colas equal to the one. I never top a strain i haven't grown before, and when im doing it for the fitst time on a strain i will grow 4 plants, top two of them and grow them all alongside each other and compare the difference, northern light derivatives normally quite like being topped, as do skunk #1 and hashplant. I personally found that the kush seeds i had a while ago didnt like being topepd but im not totally sure i was happy with the supply of the seed genetics to begin with (i don't believe it was exactly what it said it was, was not from a bank).
So, all you are going to end up with now, is a plant of natural shape, doing its thing. Also, a point to note, when a plant enters flowers, stop f***ing about with it and let it do its thing, veg is the time to do anything, once you start flowering water and a little feed is all you should be doing.
(Anyone know, if the topability of plants is related to the indica/sativa content or is just more individual to each strain that that, I've thought about this a bit and thought mayve indicas dont like being topped so much as sativas, any thoughts on that?)
-Mor