Howdy. I am making a transition to Bard as a main for Endwalker. I have a simple question for anyone here that knows Bard stuff. I am trying to pin down my rotation priorities and I am making good progress, but all the guides seem wrong on Apex Arrow. They all say to use it when you are at 100 Soul Guage, but that cannot be right.

Does anybody know the damage formula for Apex Arrow's potency? I tried looking online, but I can only find information that reflects what the tooltip says: at 20 Soul Guage, the potency is 120 and at 100 it is 600. That seems like a linear growth pattern to me, 30 potency for every 5 Soul Guage. If that is the case, then it would be logical to fire Apex Arrow any time after around 45 Soul Guage and before you reach 100. If you always waited until 100 Soul Guage to use it, then there is a small window during the time you reach 100 and before you use Apex Arrow that you might earn Repertoire that goes to waste, because you are at 100 Soul Guage.