Fading timing is done via the Step property which determines how fast the operation occurs. The higher the step number the faster the fade in. Internally the code runs a loop between the percentage specified and the step is the stepper for the loop. So step one means 100 steps, step 4 means 25 and so is 4 times faster (and less smooth). Realistic values are between 1 and 5. Anything bigger will likely to fast to notice or too rough.
o.wwControl.Fadein(Step,Percent,FinalPercent)
Percent
FinalPercent