POI can change from index finger to thumb trigger, or thumb trigger to thumb trigger. The jaws can cause different amounts of torque on the loop and string, it can cause different amounts of contact on your face which affects POI, etc. My TRU Ball ST-3 and my Carter Just Cuz impact in different places.

I haven't shot an index finger release in years, but when I did still and swapped back and forth between releases my anchor changed, as well as my loop length to accomodate this. My loop length can also change from different types of thumb triggers depending on the distance from my fingers, and the jaw/caliper/hook.

I'd really recommend taking as many shots as you can on the blank bale to get to know how to shoot this release without aiming at anything, but I guess it really boils down to how much commitment you are willing to make to get a super clean shot execution. 100% of coaches would tell you that you should not be aiming at anything for the first severalthousand shots at least when changing to a thumb trigger for the first time, but for most people it isn't worth that type of work to them. It really boils down to what you want to get out of it I guess.

That book will be at your place tomorrow, I'd suggest reading through it first before really doing much with that release. It's probably the best resource published today to teach you how to properly setup and execute that release in a repeatable manner.

Edit** Looks like Matt beat me to this while I was typing this novel......[8D]