That's because September 17 is the date on which the amendment was announced.
On November 1st, 2018. See this statement in context.
On November 1st, 2018. See this statement in context.
November 1st, 2018 / 10:35 a.m.
Director General, GST Legislation, Sales Tax Division, Tax Policy Branch, Department of Finance
That's because September 17 is the date on which the amendment was announced.
See context to find out what was said next.