I've been shooting about 2 months maybe 2,000 rounds in my life. I did some private instruction. I was taught to use my index figure.
I use the range gun a CZ 75 Tactical Sport I've done 1,000 rounds with.
I bought my first gun yesterday a CZ 75 B Retro. I started dry firing it...a lot. I found using my middle finger there was less to no movement. So...I web searched and found this forum and this thread.
I'll try soon and see what works best for me. I have a hunch in slow methodical shooting the middle finger might work fine/better on this gun. On the TS (and TS2 my kid is giving me) the trigger being so light I expect the index finger might be better.
I'm 60+ so likely I'm going to just be a target guy, but I liked the grip with two fingers on the grip and index guiding that felt better to me. I have big hands and preferred the index below the slide. I'm sure the instructors will not approve.