Here comes a lifesaver, as vozochris has created a Weakaura that tracks the timing and spawns of the goblin portals for the Greedy Emissary event! It’s a very simple one, with a progress bar showing how long until the spawn and where it’s happening.
The addon seems to be working for both EU and US servers, but in case you are having issues, try re-logging. You can also check out all the rewards and event duration here. And in case you don’t have Weakauras installed or don’t know what they are, here’s a quick guide for them.