NW's current site only allows you to pick your own seat 90 days in advance. I was wondering if this is exactly 90 days before the particular flight is scheduled to depart (down to the minute) or if it's just that - 90 days (meaning seat selection opens up after midnight).

Does anyone also known when NW starts blocking off seats for passengers with special needs? If my memory serves me right, it's not done automatically when seating opens up.