See yet - WordReference.com Dictionary of English, adverbial use #1.
What does this "yet" mean here?
In "haven't you finished packing yet?" or "He hasn't packed yet", it would make sense. I remember reading in a grammar book that in this case "yet" doesn't have to be interpreted.
17)W:Andrew, have you finished packing yet?
M:Yes, I'm all packed up...
Have you (done something) already? (I'm surprised you are finished so soon but evidence suggests you are.)
Have you (done something) yet? (I believe you should have finished by now but I'm not sure you have.)
Haven't you (done something) yet? (Evidence suggests you have not, and I'm surprised because you should be finished by now.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.