Using vibration metronome for time.
I download one form the market.
Set it to 120 bits/min to give 0.5 sec vibrations.
Follow zero; when time starts count it as one vibration.
Then 2,3,4,5, than again 1,2,3,4,5. In total it is 10 vibrations but it is 9 intervals of 0.5 sec which makes it 4.5 s. It is nice time to clock rotor but since I count 5 one set of 5 is 2 sec long and good to use for VB2.
Trying to have same count for rotor and ball to not make mistakes.
After clocked rotor, the difference what rotor make adjust by 2 times or 3 times if predicting earlier.
Then observe to catch the ball at that position and the moment the time starts. Count 5, read number if time started earlier adjust, if time then predict. Getting pulse every 0.5 sec gives many opportunities for ball to come to suitable position, around place where need to start time or perhaps at opposite side then invert result.