It wasn't perfect yet but it is now!
All three examples are different takes.
We MUST invoke the symbiotic relationship and "earliness" parameters of my full discovery with the a finger!
My original technique discovery makes this possible as follows, here is how I did it:
Training the a finger to begin "coming in" towards its string through the sole activation of the a finger's tip joint, at the precise moment that p strikes its string is extremely difficult, but it is the KEY to tremolo. The a finger must always and only do this from "fully relaxed out tip segment" status.
Also we MUST invoke the "lightness and tightness" symbiotic relationship that I've discovered (see full description section of linked video) with the extraordinarily narrow or tight or immediate tip joint contractive trajectory during that joint's SOLE activation, focusing on the finger that follows p or is used you simultaneously with p.
We must ensure that we are using an extraordinarily narrow or "tight" or "immediate" tip joint contractive trajectory during that joint's sole activation, such that it's as if there is a piece of sticky dust that is stuck upon the underside of our nail.
We are attempting to fling that imaginary piece of sticky dust straight up so that it would stick upon the underside of our plucking finger's own large/ main knuckle joint.
This, coupled with the "earliness" parameter that I've discovered, ensuring that the a finger begins coming towards its string (using only the tip joint of the a finger to do so) at the precise moment that p strikes it's note, is what is causing what you see on the video.
Both of these parameters are crucial!
Never activate either the middle joint or the large/ main knuckle joint at any time for any reason; simply allow them to move as they must, in response to the tip joints sole contractive action, for both bringing the finger to the string and plucking the string.