Min Imu quest *spoilers*
 

Hello
I'm on Triada path, got the quest to kill Min Imu but I need some help
I chose to wait for update from that USS guy but nothing happened for a long time
Then I reloaded and chose to go to Dalled but again I waited for an eternity and nothing happened
Am I missing something?

If you choose to wait for an update from the USS agent, you have to wait and intercept a neutral Triada cruiser (a Stone Arrow, if I'm not mistaken) that's escorted by a 2~3 escort wings (or 'teams').
They will head directly towards the gate you came from, so just take a straight path towards Dalled portal or just wait in the middle of the Deosis system.
Having an advanced sensor unit (like Quasar) is a plus, but not necessary.
Just look for a convoy (a.k.a. a bunch of yellow symbols on the map), and make sure to manual attack the cruiser (Ctrl + click) before it passes your mothership (especially if you use Astarte without any engine boosters), or just use your fighters to manual attack it.

HTH.