far from ready, you usually want 80% 100% pistil to turn orange/brown at the time of harvest

this is usually when you look at the trichromes inside the buds and checks for the ratio of amber vs milky and clear

you have weeks to go yet, im growing a tangerine dream at the moment , although mine had calcium problems so its looking rather stunted , i am hoping it fattens up at the end .
i think you are right about potassium, you can lock out potassium by giving too much nitrogen or magnesium because these three compete for space on the root system, so i would imagine giving too much cal/mag for instance would lock it out . Overwatering will lock out nitrogen first then potassium, and i was wondering if this is your issue because those leaves seem to be curling down ? bright led lights will also lock out potassium via stress . you can tell its potassium because the leaf edges yellow leaving dark green veins. Im no expert , ive killed plants every other way but ive never had P issues, (im wondering now if thats because i have a low end light so almost impossible to light stress a plant) and i see those purple stems coming up out of the soil and i am going to go for overwatering AND light stress.