Should "have" in "I have finished packing by 5pm" be dropped?

> 现在完成时态，本质是一种“现在时”。不管有没有时间状语的存在，
> 它总是与“此时此刻”联系起来的，所以它不能与确切表达“非现在”
>（过去、或将来的任何时刻）的时间状语连用，这里的by 5:00, P.M.
> 就是一个“ ...

So the sentence "somebody has done something by 5pm" is wrong? Example:
A: You're ready to go?
B: Yes. I have finished packing by 5pm.

Actually, I asked two native speakers, one white (John) one African American (Jack), and here's what they say.

Yong: Is this sentence grammatically correct? "I have finished packing by 5pm." Or should it be "I finished packing by 5pm."?
John: I finished packing by 5pm
Yong: No "have"?
John: correct no have. I think they are both technically correct
Yong: Technically correct. I love that judgement

Yong: Is this sentence grammatically correct? "I have finished packing by 5pm." Or should I drop "have"?
Jack: I am not sure what context you are using the sentence in. Currently the way you have presented the sentence, it would be ok
Jack: either way
Yong: Consider this dialog:
A: Ready to go?
B: Sure. I've finished packing by 5pm.
Jack: then i would say "i finished packing at 5pm"
Yong: OK. Thanks. I asked another coworker here and he prefers that too, although he says they're both "Technically correct"!
Jack: that is true