Thomas, how long has construction been happening? There's no hard limit when it's "too late" to do an NC certification, but I've generally heard that when CDs are fairly complete or when construction has started it is very challenging to pull off. Not only might there be requirements that yo have to scramble to try to meet (or might not meet), but you might have to work hard to find documentation (and need the cooperation of people who might have moved on to other things).