If you did the prompt as an exponential slowdown to a terminus pause, then players who respond and decide quickly (within the first second), would not experience any actual interruption, since the action would still be tangibly moving. If you wait longer, it slows more until it reaches the full pause point to wait for you. That would allow for the option to put a time limit on them smoothly as well, if people want that, since the slow-to-terminus could just as easily be the aesthetic depiction of your time limit.
