I had expected to be near my objective "by now," ...

[sitifan]

I stopped to let the car cool off and to study the map. I had expected to be near my objective by now, but everything still seemed alien to me.
http://edu.szmdata.com/NCE/3/Lesson 57.html
In the above quotation, can I replace "by now" with "by then"?

 

[Tarheel]

Yes. The phrase "by now" seems odd to me there as it implies present tense.

 

[tedmc]

"By now" gives a sense of immediacy, though "by then" goes with the past tense. I have seen both used.

 

[5jj]

The phrase "by now" seems odd to me there as it implies present tense.

Now is often used to mean 'at a particular time'. By now can mean 'by a particular time'.