When does time happen?

Does it occur in discrete moments? Or as a flow?

If the change is occurring at a pace that is too small for me to notice ("experience"), then I can't "experience" it, right? I'm not convinced that I "experience" time.

Reaching way back into the dusty caverns of my memory, I think I remember from high school calculus that the whole point of calculus is to measure the change that takes place at a "point" -- remembering that a "point" has no space itself and, if thought of as a point in time, is instantaneous. It's a helpful construct, because since time and space are made up of an infinite number of "points," none of which have any space or take any time themselves but all of which added together make all of time and all of space, then we are kind of stuck with a model that requires instantaneous change. And if change has to occur instantaneously, then change doesn't necessitate time, right?

Peace.