it's a little late to do too much about it now, most of the time that develops during the stretch. they're putting out a lot of new growth during that time, and still need some N to feed it. you should keep feeding it what you were feeding it during veg, a little stronger than your veg mix, till you see it start to produce pistils, then over a couple of feeding transition to bloom nutes.
you don't want to give it too much N now that it's started flowering, but you might want to feed it just a little stronger than you are