They've had their lunch. (already)
They've already had their lunch.
Wow, have you finished cleaning? (already)
Wow, have you already finished cleaning? / Have you finished cleaning already?
We've been to the museum. (just)
We've just been to the museum.
I haven't done my homework. (yet)
I haven't done my homework yet.
I've eaten breakfast. (already)
I've already eaten breakfast.
Have you spoken to your teacher? (yet)
Have you spoken to your teacher yet?
Hasn't he finished his homework? (yet)
Hasn't he finished his homework yet?
I've come home from school (just)
I've just come home from school.
They've written the blog post. (already)
They've already written the blog post.