I just sort of consider these "after-losses", they're the losses that come in the hours and days after a significant loss, the one we know and consider when we lost, "this time".

We can both reset our clocks now I suppose, but in the end it will never be more accurate than "oh it's been months" or "I haven't thought of that in a long time", "maybe a few years", "nearly a decade"

So we can keep time from the date of the inciting incident I think