I could understand a vague, "Uh, I don't remember where we got them or when," but a very detailed description of their origin and their purpose seems, again, like way too much detail.
They're good at that, though, aren't they? Putting all the little fine points on things? Maybe it'll seem more believable that way.
If it were me: "Uh, I think they came around 6:00-ish, but I'm not sure."
Damon: "Brenda was in the shower when they arrived. I remember because I could hear the water running upstairs from where I sat playing video games with the boys, while Danielle was hunched over her diary at the table, where she had been for two hours previously. But I could hear the water, I could definitely hear the water."