In general, if stocks moves closer to or pass your short side of the spread, it is time to consider roll it down. But I also use elliot wave to see if the current wave down is close to completion, in which case, I sometimes would take a chance and not roll it.
But in a clear downtrend (ie, still in the middle of wave 3 down and not even seeing wave 4 and 5 yet), it is a good idea to roll it down
