Since the room is massive, it's recommended to stack in the center of the room every time Nidhogg flies away, then spread out to avoid the AoEs, thus ensuring you can get positioned in time. The holes will spawn first, Nidhogg will disappear and you will be able to see from where he flies to where the trail will go.
Unlike the previous encounter in The Aery, this fight has four phases that combine healer checks, DPS checks, and raid mechanics (such as stacking to share damage).