According to the wiki, you start the quest with Old Lady Gibson, wait nine days, speak to Ignacio Rivas, wait two days, then talk to ED-E again. Gibson didn't give me the dialogue option needed, though, so Rivas started the quest. I tried sleeping through two days, that didn't work, then nine days, and that didn't work either. Since I started with Rivas, does that mean I need to find a different second person to talk to? I'm almost at the end of the game, so just lugging him around for a while isn't really an option. There's nowhere to lug him, except as I run around trying to find (then do) Arcade's quest.

Sometimes i get the triggers very early in the game. This time around though, i'm quite progressed into the story and have yet to get the 2nd trigger.
Think it varies alot.