I have done something now

[kachibibb]

Normally, present perfect tense comes with time adverbs like already, for, since, ever, never, etc.

But do native speakers accept "now"? I remember some accept putting now into present perfect sentences like this:

Now I have done my homework.
My French has now improved a lot.

But not the end of the sentence. But what is the reason?

I have done my homework now.
My French has improved now.

 

[5jj]

All four of your sentences are grammatically possible. What made you think sentence-final 'now' was not possible?

 

[Tarheel]

What does "now" add to any of those sentences?

 

[emsr2d2]

It adds nothing to the sentences as they stand. It would be more appropriate as part of a longer dialogue. For example:

Helen (at 6pm): Have you finished your homework?
Tom: Not yet.
Helen (at 8pm): Dinner's ready! Have you finished?
Tom: I have now! Yay! I'm starving!