A: “Is the package from Head Office here?”
B: “No, it hasn’t arrived yet.” (B expects them to arrive in the future)

A: “Can I watch TV mom?”
B: “Did you do your homework?”
A: “I started but I haven’t finished it yet. I need a break.” (The homework is incomplete)

We can answer a question by simply saying not yet.

A: “Can I watch TV mom?”
B: “Did you do your homework?”
A: “Not yet.”
B: “You can’t watch TV until you do your homework!”

“I wonder why the bus hasn’t arrived yet?”