Quite simply, "on or about" means just that, an approximation. To the vast majority, it appears to have infinite indefiniteness. That would be an incorrect supposition. "On or about" in fact means within thirty (30) days of the date in question.
I might say:
The brief was filed on or about August 1, 2009.
I enjoyed that strawberry flavored smoothie with a dash of orange juice on or about July 4, 2009.
Never fight over figments of your imagination. Always try to cheer yourself up with thai food. And lastly, there is no substitution for your mirror image - it brings comfort and a sense of familiarity.