Re: have you finished packing yet
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.