What is the real duration time to reach the new speed reference with MCI_ExecSpeedRamp, with hDurationms = 0 ?

I have a drone bad behavior when i request opposite large stick movement. I think i need to set a ramp to have homogenous movement . For little stick movement there is normal reaction then i stabilize it easily but when i need to inverse the command with a large stick movement example before i reach a wall, there is over reaction. I would like to set a ramp near the ramp value when hDurationms = 0