Looking on the internet deeply has found these results:

postpone a week is the most popular phrase on the web.

postpone by one week 111 results on the web	postpone a week 1363 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
For every week of subpar training (with a cold, for example), postpone by one week. The trickiest situation is when you're feeling excessively fatigued. There's a �... Nov 2, 2012 ... CAIRO (AP) � An Egyptian minister of Friday said the government in Cairo has decided to postpone by one week the imposition of a curfew on�... Sep 23, 2014 ... For every week of subpar training (with a cold, for example), postpone by one week. The trickiest situation is when you're feeling excessively�... Jan 12, 2014 ... Unlike previously informed, the 2014 event date is Saturday 6.9. We had to postpone by one week due to a double booking in the event center.	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

postpone by one week

111 results on the web

postpone a week

1363 results on the web

More popular!

For every week of subpar training (with a cold, for example), postpone by one week. The trickiest situation is when you're feeling excessively fatigued. There's a �...
Nov 2, 2012 ... CAIRO (AP) � An Egyptian minister of Friday said the government in Cairo has decided to postpone by one week the imposition of a curfew on�...
Sep 23, 2014 ... For every week of subpar training (with a cold, for example), postpone by one week. The trickiest situation is when you're feeling excessively�...
Jan 12, 2014 ... Unlike previously informed, the 2014 event date is Saturday 6.9. We had to postpone by one week due to a double booking in the event center.

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.