I just read where diffuse axonal injury is largely a matter of secondary biochemical cascades, and not directly a matter of the axonal shearing from the primary injury. This would account for the delayed onset you both experienced (and probably me, but I can't remember that far back).

It is this cascading that causes the actual death of the neuron, and so you heard correctly about it taking a while for the cell to die.

Perhaps Mark in Idaho can jump in and fill in some details.