The default apex date picker shows Sunday as first day. But I can see on your example, the default apex date picker has Monday as first day. Is there a way I can also make my default apex date picker to show monday as first day.Good question BHavesh, I wasn't entirely sure how I did it either. It wasn't a conscious decision on my part, but a quick look with session debugging on revealed the answer, as you can see in the image below.
NLS_TERRITORY specifies the name of the territory whose conventions are to be followed for day and week numbering.So there's your answer - the territory setting establishes the week numbering. And where to set it in Oracle Apex? See below.
This parameter also establishes the default date format, the default decimal character and group separator, and the default ISO and local currency symbols.