Thanks for the reply. An “instant” is also a matter of belief. There is nothing in the physical world that happens in an “instant”.
True, there’s no scientific unit of time called the “instant.”
But there is such a thing as meaningless quibbling.
From the time you flip a light switch, to the time that the light bulb heats up sufficiently to enable you to read, do you tap your feet, twiddle your thumbs, have a cigarette?