Thanks to the clipping files at the History Room of the Oakland Public
> Library, I have been able to pin down the date that San Francisco and
> Oakland went fully to 2L-5N numbers: August 10, 1947, a Sunday, at 12 > midnight.
I don't believe any telco has done a cut on Sunday night. It was typically Saturday night (or perhaps 2:00 AM on Sunday) in early post WWII years. Then, Bell tended to do ESS cutovers at 2:00 AM on Saturdays, so they would have the weekend to work out kinks.