It would take about 8 hours for such a plume to spurt out. You cannot see the motion of a prominence when you view it through an amateur telescope.
This was a whopper, all right. Had it been pointed at Earth the damage could have been historic. There are other factors also. It strongly depends upon the direction of the Earth's magnetic field as compared to the cloud's magnetic field at the time the cloud arrives at Earth. If it is opposite to Earth's it will facilitate the particle's journey down our own field lines, if oriented the same, it will bounce away.
It usually takes about two days to get here, however if another Coronal Mass Ejection, CME swept space clear a day or so earlier, the new one could get here in less than a day.