see the due date in your statement.
should be 28th + 20 days.

same with other cc: 20 days after statement date.

you can find out from the Statement.

28 Jul statement = 17 Aug due date
28 Aug statement = 17 Sep due date
28 Sep statement = 18 Oct due date
28 Oct statement = 17 Nov due date
28 Nov statement = 18 Dec due date
i generally dont like due date that's crossing month, cuz i cant follow the exact due date. some months 1 day early, some 1 day later

i prefer statement date early of the month, so that due date (+20 days) will fall within same month, so the date is always "fixed".

+20 days.