Originally Posted by
themicah
This is somewhat misleading. NW does NOT always let non-elites select P and E seats at the 24 hour mark. Anecdotal evidence suggests that the more full a flight is, the more likely the seats will be released right at 24 hours. But I've never seen a thread confirming the exact criteria. There are many threads on this subject.
For the OP, this is still the best course of action. In my experience, I've never seen a non-elite denied access to those seats at the 24-hour mark. Not saying it doesn't happen, but I've never experienced it. However, I'll edit my post accordingly.
Now, if it is a connecting itinerary, you cannot select P and E seats for the connecting flight until you are within the 24-hour period for that flight's departure. For example, if you are scheduled to leave PHL at 6am and connect in MSP onward to SEA at 9am, you could select P and E seats at 8am the day before for the PHL-MSP leg, but not the connecting leg.