Conventional wisdom, at least in the United States, is that the end of the week is Sunday because school starts on Monday, and the business week begins on Monday as well. However, it is a common axiom that Sunday is the beginning of the week, with Saturday marking the end of the prior week. (Just looking at my New York Yankees calendar, though it may be made in China, a new row, representing a new week, starts with Sunday and ends with Saturday.)
In regards to the release of the Guardians, they should be out during the first week of October. There may be complications with the Second Edition, causing a delay in its release, or theory11 may simply wait another day, week, month, or year to release them (though hopefully not).
Cheers,
JTM