first thing never plant more than one in the same pot!!!!!! so transplant those into separated containers#2 get the light closer cuz they are stretching...
then after they have been transplanted and under closer lights for a week or two and then cut off the very top 2 leaves. this will create 2 main stems.. research topping and fimming cannabis
There's Uncle Ben's method, above the 2nd true node(on the main stem, from bottom: sucker leaves, 1st node, 2nd node), pinch there, and you'll get 4 main colas. He suggests doing it when your plant 4-5 'nodes old'. Which seems right for your plants. The reasoning behind it, in English, is better root structure, less stress, and most importantly redistribute the 'ho moans' to the lower foliage producing 4 main colas.
As they staand, there isn't any room for them to bush out without growing into each other. I'd just kep it like it is until you can identify the females, then take clones and start from there.