Using other cases as a guide, I would guess PSP will start 30 days after a ruling is finalized, not announced, but finalized. Once they start, it will take 5-6 months to finish.
Since anyone with an unexipired 15 year or longer registration period will be staying on the registry, it won’t rake long to remove those with a Pre- Sorna unexpired 10 year registration period.
I expect new challenges to 1952 to take us through the new year and into 2019 at least. Maybe even longer.
So I don’t know how they can expect those who have completed their original Pre-Sorna registration periods to continue to be in compliance until they receive a letter.