I don't use the joint, but I do use the part of the finger pad closer to the joint.
If you look at your finger, and divide the first portion from tip to joint into thirds, the middle third is the area I use most of the time, the center of the pad of your finger... On small gripped pistols, I use the last third, closest to the joint. I have less twisting that way, because I am not forcing my finger to bow outward like it would if I used the center of the pad...
As I said, its dependent on the pistol's size. Larger pistols or ones with longer trigger reach, like my Sig 226 and CZ 75, I use the center pad. My CZ in full DA mode needs me to use closer to my tip, due to the long reach...