Teusday the 30th
The last day of Ramadan in 2008 is September 29th!
The last day of September can be any day of the week
AIG closed the day of September 15th 2008 at $4.76 a share down almost 61% from the last trading session.
September 15, 2008 was a Monday.
September 6, 2008 was a Saturday.
19 September 2008 was a Friday.
September 20, 2008 fell on a Saturday.
September 16th, 2008 fell on a Tuesday.
September 16th, 2008 fell on a Tuesday.
September 7, 2008 fell on a Sunday.
You would use "last" if you wanted to say "last year", "last September" etc. If the event happened 2 September's ago, for example, you would use "on" to state the specific day. For example, "She died on September 3rd 2008".
It was a Tuesday.