I am thinking that these would have secondary effect but for accuracy.
1 MPH = 1.47 ft/sec
Average Stride = 6 ft
0.7 secs = 5.8MPH
For every 0.1 sec difference you are talking about 1 MPH in average velo. However once foot strike happens linear velocity is converted into rotational. Also remember these are average numbers in actuality there is a velocity and acceleration curve.
I believe intent to throw hard and hip drive are huge in the velocity equation, so I would work on this first and worry about timing it maybe later.