You should be doing it now and not drag it out, just compare what you presently do and if it matches up with requirements in 9K15, document it and move on.
Not that much has really changed...How do I know? I'm doing a Transition audit right now and these for barely changed anything and they're doing fine.
Get past the hype, the BS, hand wringing and tear shedding and get it done, you'll be surprised.