Although NY is probably seeing an explosion in infections, this doubling is probably not a true growth in number of cases overnight, but instead representative of massively increased testing in NY.
This is far from over.
But an actual doubling, measured by the number of people who can't breathe in a hospital currently takes 3-4 days.
Not that I think the number of cases is grossly overstated, but Italy lists deaths from coronavirus if the patient dies for ANY reason while they are afflicted by the coronavirus. This would be the source of some "fudging" of the numbers.
One country (Germany, I think?) doesn't or wasn't including people who weren't tested before dying, so had a really low rate.