Crab, the aircraft are not "grounded" as the certifying authority i.e. FAA, have not made the ASB mandatory by issueing an AD.
Quite why the FAA have chosen to drag their heels is a mystery.
However the operators will no doubt take a sensible attitude when it comes to compliance. A voluntary grounding?
As to your question about timescale. I am sure it varies from location to location. Perhaps some aircraft have already been modified? Over here in the tropics, we should have the final pieces of the jigsaw on site by Monday. Flying Tuesday - maybe?