Is there a way to say I don't want to file injured spouse so that the offset can be paid prior to 6 months?

If you already filed a tax return, there is nothing you can do to cancel or change it.

If you have not filed your tax return yet, you are not required to include the injured spouse form. Or, the injured spouse form may be filed separately, after the joint return has been processed.  (For example, if you file a joint return and the refund is offset unexpectedly, you could file the injured spouse form later to request a partial refund.)