It depends on the school.
Public or private.
Whether it is an I.B. (International Baccalaureate) school or not.
But it seems, things taught are just getting more and more accelerated. Per grade. ie: kids learning things 1 year ahead. Ready or not.
My friend's son, who is in 4th grade, private school, is learning it now, in a concentrated manner.
Versus, my daughter, was learning it in 3rd grade. In a concentrated manner.
Then previous to that, it was introduced, in a more younger-aged-kid way, in 2nd grade.
Then in Kindergarten and 1st grade, they do simpler forms of it. ie: grouping, skip counting as the previous poster said etc.
My son is in the 1st grade, and for us, on our own and per my son, we are teaching him multiplication. And he gets it.
But again, teaching things, per age/grade.
ie: teaching multiplication to a 4th grader, is different in concept/explanation than it would be for a 2nd grader or 1st grader.
Then what about fractions?
My son in 1st grade is learning that too.