Neo_007answered grow question 4 years ago I personally would start with the directions on the bottle.
If I recall correctly, it is not advised as a single source nute, designed to be added to your bloom mix.
If thats right, what I would do, is follow those directions ( confirm it first ), thus add whatever your bloom nutes are, then the coolbloom, based on the measurements it gives you, then check the TDS via a PPM meter. If its coming in high ( personally at a similar stage I watered with 1300 PPM and noticed only 1 plant show the beginning of nute lockout, burnt leaf tips ), so lets say it comes in at 1500, and you want to play it safe, dilute down to the PPM target you have set for yourself.
Then PH it according to your substrate and target PH, then rock and roll.
I can take a look at your plant photos to maybe expand on this, but thats what I would generally do in your shoes. I also would not necessarily hit with a finishing agent right before cutting, while Im personally not a big believer in the value of flushing, I understand its common practice so would likely recommend it when using nute salts instead of organics.
Looking forward to other answers as well .