stepper motor minimum delay
You do not state the rotation rate you want, so I'll give you the time required for a single step from rest. Obviously, once you get the load spinning, the step time goes down. However, as speed goes up the available torque goes down, so at some point the load losses balance the torque available, and no further acceleration is possible. Additionally, at some point the inductance of the motor will prevent the winding currents from changing, but that is a more advanced subject.

1 - From the motor data sheet, determine the motor torque T at your desired current.

2 - From analysis of your load, determine the load angular moment of inertia.

3 - From the motor data sheet, determine the intrinsic motor moment of inertia, and add this to the load MOI, and call it J.

4 - Using the results of 1 and 3, determine the time required to accelerate from rest to one step angle theta, where $$ \Theta = \frac{T\times t^2}{2J} $$ or $$t = \sqrt{\frac{2J\Theta}{T}}$$

You need to be careful of your units, especially Theta, which must be in radians, rather than degrees. Also, this assumes no frictional losses in load bearings or something similar.

This is a very conservative number, and depending on the motor you may be able to get away with about 70% of this step time.