Other than the requirement for using the Ten Blessed Methods (July 21
2017), and the requirement for constraints on email intermediates
(January 15 2018 for existing intermediates), all of the new provisions
are effective immediately. You can see the differences here:
https://github.com/mozilla/pkipolicy/compare/2.4.1...2.5
There were a couple of changes post-review; I added a deadline, and we
also made it clear in our policy what is clear elsewhere, that audits
must be yearly, period-of-time, and contiguous.