I would just stop with the nutes altogether, clean up the yellowing fan leaves, and just ride it out until harvest. Like I said, get a microscope and harvest by the trichs, If those pics you posted were of what they looked like when you said there were "a bunch" of yellowing leaves, it actually didn't look that bad, just like a plant that needed some defol. It's normal for a plant to fade and drop lower hand leaves, even throughout veg.
I think a lot of people new to growing are way too panic-y. When you start piling up all these knee-jerk reactions, it usually leads to garbage in the end. You could literally take some quality beans and throw them out in a sunny field that receives a little bit of rainfall, leave them alone until October, and end up with better bud than the person who spends $1000 on equipment and nutes and babies the plant too much. Not criticizing, just saying -- less is more.
it’s that time of year! You are far from being alone.
