Stand still throws help, because everything moves slower. If you start the pinch early like, when you start the elbow chop you should not be late with the pinch. As long as you realize, that the pinch needs to start fast and be hard. Once that works try adding steps until you're at full speed. Then it should be easier to move the onset of the pinch later to see, if you gain or lose D now with it. What you achieve now may not be, what works best for you later, if you train for a different timing.
From muscle resistance point of view a fairly late pinch would allow a faster arm motion. But once you factor in the need to fight the bending back of the wrist once the elbow starts to straighten, things get complicated. The better you are at wrist part of the snap, the earlier you can probably get away with pinching. That means, that with changing form and muscle power with possibly changes in nerve speed your pinch timing may change over time. If you want to get the best results, So you should check the timing each year.
There's a young gun here, that squeezes hard from the get go and never varies the squeezing power. He says he grips firmly with the fingers inside the disc and has a fairly loose thumb atop the disc. That comes from the perspective of a strong guy. I heard him have a slip last summer and the sound was more like firecracker going off than a pop. It was really loud so he must grip way harder than i can at full power. I've never heard anyone else make such a loud sound from throwing. It goes to show, that once you have excess of power you can get away with almost everything and still have the disc sail past 200 meters in wind. He has done that in a storm. According to Ville Piippo this guy throws the fastest backhands in Finland. People have spoken of well above 120 KPH radar measurements, but the radar is not necessarily accurate so exact numbers are a mystery. If i recall correctly he has thrown 600'ish on flat land without that much wind, but i don't have exact details. By the way he is not that tall. He may be the shortest 200 m thrower on flat ground and i don't think the shot was made that much above sea level, so it is a great result indeed. Transfer that to Primm and there's potential for much more.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.