|Jadefang Untamed, Tamed, & Non-Combat Companion pet|
The spawn timer on Jadefang seems to be between approximately 6-12 hours.
Jadefang can be found at 61.3, 22 in Deepholm in the Crumbling Depths. In the screenshot below the tiny blue square on the map indicates where this is. The entrance is located at 58.3, 25.8. Note: It is possible for NPCScan to pick up Jadefang while not inside the tunnel. Mine went off once while I was flying toward Therazan's Throne just above the spawn point.
Jadefang is not an easy rare to get to. There are only a few ways to get to Jadefang. Probably the easiest way is to get the Underground Economy daily quest from Ricket. This is a goblin NPC located just inside the Crumbling Depths. (This quest will only become available after you have completed the entire quest line in Deepholm leading up to the Therazane dailies.) You will need the Bombs from this quest to get to Jadefang. This daily quest is not available every day. I actually recommend grabbing this quest when it is up and coming back on a day when it isn't. This makes it a little less likely that other people will be able to get to Jadefang on that day. Follow the path further inside, once you are past the Colossal Gyreworm you will be in a large chamber. Head into the tunnel on the right side (see screen shot below).
I have read that engineers can get to Jadefang as well with their Rocket Boots when they malfunction and that Goblins can use their Rocket Jump racial. These methods require a lot more time and practice (and luck) to get right. I personally recommend the bomb method.
I also helped a friend get to Jadefang recently that didn't have the daily by dying just outside Jadefang's cave entrance with my night elf priest. I rezzed on the ledge and used my Leap of Faith to pull her to me.
For your viewing pleasure I have another video below that demonstrates how NPCScan and Silverdragon will both pick up Jadefang from outside the cave and exactly how to get to him.
And the hunter tame: