It is getting late in the year so I would only go to CYA of 60. Your FC usage is going to start dropping pretty quickly.
You can do that now, and adjust your FC accordingly with bleach.
You do add salt. For a Pentair add enough for 2800 ppm. Check your salt level in the pool before you add. Use Pool Math. Then adjust to 3200 ppm unless you know your pool volume very well then just go to 3200 ppm first.
Brush/mix and run the pump to distribute salt.
You should know how much FC you are using each day now. Set the SWCG to create that much each day. Get to your target FC with bleach.
Your IC 40 makes 1.4# of chlorine if run 24 hours @ 100%. So use PoolMath to determine how much chlorine gas you need each day for the FC ppm you use. Then dial in your SWCG to create that much.
Good luck.
469 lbs assuming 0 salt level to start for 20,000 gallons. i did that right in pool math correct? that's crazy it seems? and that is just to 2800.
also in pool math i changes FC to chlorine gas to mess around. my target is 7 lets say. if i get a reading of 5 when i test i have to add 5.3 oz by weight of gas to get to 7 again. so again that is longer than 24 hrs at 100%. am i missing something?