The weekStarts property (number) specifies the first day of the week for the locale.
DayPilot.Locale.weekStarts0 - Sunday
1 - Monday
2 - Tuesday
3 - Wednesday
4 - Thursday
5 - Friday
6 - Saturday
0 // SundayUse an integer from 0 to 6, where 0 represents Sunday and 6 represents Saturday.
const locale = DayPilot.Locale.find("en-us");
console.log(locale.weekStarts);