This quest is fun, and annoying.
First, good tip from Sarongor in another post - "position yourself between two ponds at loc -2120, -472" that helped lots, and so worth repeating.
Our small group moved from the zone in, invis and up top by the ponds. The quest updates, yes we zoned, yes we got to the kill spot, now kill the hedgehog!
First test was the drakes. They are indifferent (yes, invis was off!)
So can take as long as you like, no problems. In the hour or so we were there, no mobs patrol that engaged.
Yes, as others have said, when you fight the hedgehog the drakes are sociable. The one beside that spot will fight. You have a choice, kill it first while wait for the hedgehog, or deal with it whenever you see it. I found it useful as a spawn timer. ~10-12 minutes? not sure.
The hedgehog does not spawn in the near area of the quest, or those two ponds.
But he does run by that area.
Therefore you can wait, and tag him as he goes by. He is non-aggro, until you make the first move.
for me... a hot button for:-
/target a_hotsprings_hedgehog
... was useful.
Believe me if I say, you won't see the hedgehog coming. Trying to mouse click it, he's just too damn fast and he's out the way again.
Therefore for me, was spam that target button, and as soon as i had a target - then click the aggro spells. Stun? Snare? whatever as long as its quick to cast.
If you don't get him, it will take few minutes from him to do another lap of whatever path he is on and come by.
One of the concerns we had, was he triggered, like some other quest events.
I think safe to say the answer is no.
Our group came in, we all got updates and were all at the "kill it" stage.
Yet he did respawn, and come back around again, similar timing as the drake by the pond. Only difference being drake is static and right there, whereas the hedgehog does his merry little journey.
All in all, if you plan for about 15 minutes or so, per group member doing the quest you should all get his head for turn in. No need to run around, back to quest giver, one person at a time. Just keep the group together by the pond, and wait.. spam that key and get the hedgehog!