It is too late to be feeding nitrogen. It's time for a bloom formula...low first number (nitrogen), much higher middle and last (potassium and potash). These days I use MaxSea Bloom (3-20-20), but Alaska Morbloom (0-10-10) would be just fine for you...much cheaper but still organic.(MaxSea is not entirely organic, but who's kidding who, it's from Garberville.)
Must respectfully disagree re: the yellow leaves. Earlier in the year, it's probably a nitrogen deficiency if there are a lot of yellowing leaves, but these are old fan leaves who have done their job and spent all their chlorophyll supporting growth. It's the end of the growing season. Look around at the trees! If they aren't changing color yet, they will shortly. They've done their job, and the only thing they'll do now is wilt, cling to the stem while they rot and cause a great spot for mold. Pinch 'em off!
I would use Alaska MorBloom or something with equally low numbers. Chemical nutes at this point would shock the living shit out of these plants. First grow is a learning experience, and you've learned lots and have buds you'll be smoking from your own crop. Doesn't get much better than that!