Accorto Parameters are used for various settings. 

Go to Setup > Develop > Custom Settings

  • Click on Manage Accorto Parameters
  • Click on New (or edit existing)
    • In field Name enter e.g. FirstDayInWeek
    • In field Key enter exactly FirstDayInWeek
    • In field Value Integer, enter the year where 1/1 is the weekday you require (see below)
    • In field Value String, enter the specific locale (e.g. en_US)

Note that defining the First Day of Week is defined in the Payroll Processor now.