re use child of constraint?

I'd like to re use the child of constriant so that i can enable, and disble it without the position of the constrained bone going to unpreditable positions.

I can enable and disable it once, but once i try to renable it, the constrained bone goes directly ontop of the target bone. is there a way so that when renabling, wont sit directly ontop of the target bone, but instead maintain any offset it has when keyframing the influence back to one?