Heres an awesome tip I gathered from reading up on posts and info off the web. Once your plant begins to grow multiple branches during the flowering stage...tie a black light proof bag over one branch and force a section of the plant to start flowering much earlier than the rest of the plant. Once the cover section exposes its buds trim off the branch and if the plant is female, Let It Riiiiide.
That's an interesting idea, never tried it, my first inclination though is not to do it. Flowering is caused by a hormonal reaction in the plant to the changing light conditions. I don't see how it could be good for one plant to be getting veg lighting signals in some parts and flower lighting signals in another, seems like it would really screw the plant up. The hormones don't stay in one place, they move all through the plant. Better to take that same branch as a clone and flower the clone while vegging the plant, IMO.