British people would say "I have a meeting on the 8th day of Sep in 2019." I guess American would say "I have a meeting on Sep 8, 2019." But how to read "on Sep 8, 2019" in a natural way?
"September 8th, 2019" is by far the most common in everyday speech, and feels perfectly natural to Americans. "The 8th of September, 2019" is more formal and less common, typically only used for invitations and the like.
Additionally, in most cases the year is omitted and it is assumed that you mean this year, so 09/08/2019 would be spoken as "September 8th".