NW NE
3 -> 4
1 -> 2
SW SE
?
This is the correct, and since Helm took the Third Rampart (NW) it does not go in line with the theory "enter on the day & kill the rampart that corresponds with the route you chose on the first floor."
Helm spent 74 minutes in Zhayolm before reaching the 5th floor, so it is possible that he passed through a late Iceday, all of Thundersday and hit Lightsday as he arrived on the 5th. If the numbered ramparts are any sort of hint for earlier floors, then the NE route on the first floor corresponds to Lightsday/Darksday-- the Fourth Rampart.