If by 10:00 am it is only down by 10% or less I would say that is a good idea, however if it is down by 12 or 13% as it is now after hours, I would then think you have all day to cover and perhaps the rest of the week. Perhaps at a much lower price.
Seems to me if they drop 10% or less on earnings there could be a bounce but more than 10% they usually stay down.