When do spawn timers start?

[bsmorgan]

According to what I've read, a majority of the rares in the Tanaan Jungle are on a 30 minute spawn timer.

When does that timer start? Does it start when the rare is killed or does it start when the rare spawns? For example, a rare spawns at 1:00 and is killed at 1:15. Will it show up again at 1:30 or 1:45?

Does anyone know of an addon that keeps track of when each rare should spawn next?

Thanks.