They say yellowing is normal, but this much?

Looking very good. These makes my mouth watered. They look ready for harves. And my opinion is that you should prepare them for the next step. First, I would carefully remove all fan leaves. These are the yellow leaves. All the nutes had been sucked out and move to flower buds. This is the time to fully remove them. I find it easier and cleaner to remove fan leaves now than to trimm them off later. Do wear gloves. Otherwise your hands will be sticky and smell like ganja for a long time. Then there should be no more fertizer feeding. If you want, you can feed dilute yoghurt, 1 part yoghurt with live organism to 15 part of water. Look up "LAB" and terpenes. LAB is the microorganism in the yoghurt. They are known to make buds stickier, smell stronger, generally more taste and potentcy. Wait for the yoghurt to work for a few days then harvest. Actually, you could harvest already. And a week would makes the flowers more ripe. My personal preference is not to wait that long.