Yes indeed... they really do start putting out an aroma at about 4 weeks don't they? I hope this is manageable for you, it is only going to get stronger from this point on.
It is normal to start seeing sex at the point they start becoming mature plants. When you switch the lights to 12/12 it will force even the slow ones to show, but at 4 weeks onward in vegetative it is often times obvious who is who, what it is that they are and who it is they will be dancing with.
So if you are seeing some V pistil formations already, congratulations on your girl! How tall are you going to get her before you go to flower?

Emmie