First round:
The Southern and Western snakes progress past the perimeter, riggling underneath the sleeping horses and around the sleeping Heironeans, ending up about ten feet East and fifteen feet South from Niccolo, respectively.
The Northern-most of the Northeastern snakes (henceforth known a the Northern snake) moves and darts at Fendric from beneath Sunray. (Attack: 17, Damage: 1, Fort vs. Poison DC 11 else 1 init/1 sec. Con damage) As it strikes he is mid-yell, drawing his weapons. (Since you were placed at Sunray to begin with, you still have a standard action if you want to strike the creature...)
Niccolo, roused by the yell, awakens, as do others. He is currently prone but not flat-footed. (Essentially, I'm treating "waking up" as a full-round action... However, those with higher initiatives than the "awakener" will be considered to have delayed their initiatives -- in this case, it means that Marten and Shamil will be able to stand and act after Fendric's next initiative)
Shavah, seeing that Niccolo is in trouble, moves and attacks the Western snake. She gets a decent hit on it, but it keeps to its path.
As the others awake, the Eastern snake also darts at Fendric, (Attack: 25, Damage: 2, Fort vs. Poison DC 11 else 4 init/5 sec. Con damage), just before Nurthk leaps over the awakening Laam, bringing his axe down hard on the viper, opening a massive wound. The snake wriggles spasmically for a moment, then settles on its back, still twitching.
Round 2:
The Southern snake moves to strike at Niccolo, much more slowly than those that attacked Fendric. (Attack: 20, Damage: 2, Fort vs. Poison DC 11 else 5 init/2 sec. Con damage) (Note that the attack bonus for Niccolo being prone is already taken into account.) The Western snake appears to be trying to do the same, but Shavah is able to get a much better stab at it this time (AOO), and pins it briefly to the ground with her longsword before pulling it off with her foot.
Marten stands and moves to defend Fendric; Shamil stands, and likewise moves to defend Niccolo.
(At this point it would be the Northern snake's initiative, but I'm holding on that until the result of Fendric's attack on it comes through. Go ahead and post your next actions, with an "if" based on the Northern snake's status -- alive or dead -- if need be.)