Just use a nitrogen supplement in addition to bloom nutes. I use just enough to make the yellowing of the leaves go away. too much N will hinder flowering, so will an N deficiency.
be careful of dead/dying leaves. Its a great place for mold to take hold.
I do a tug test on my leaves when they look like they are getting close. If you can tug gently and the leaf comes off, it was time for it to go.
By using nitrogen throughout the flowering process, you should only see yellow leaves at the end of flowering when you cut back food and plan to flush.

hope this helps.