Hi,
There is nothing built-in to do this.
If your quarters are on the correct break but a different quarter you can
just type over the names of the quarter but spell is slightly different. For
example change Qtr1 to Q2 and so on.
Or
You can fake it. Create a dummy column in the source data. For example, if
A2:A100 contained your dates, then in the dummy column enter a formula like
=EDATE(A2,x)
X should be a positive or negative number indicating how many months offset
from the real month, your month should be. -1 means one month back, 1 is one
month forward.
Add this field to the pivot table and group on it.