Set Option: Model object attribute
Specifies the start day of the week to be used when calculating queries that use relative time keywords: %this_week_begin, %this_week_end, %last_week_begin, and %last_week_end. Valid entries are integers from 0 - 6, with 0 being Sunday, 1 being Monday, etc.
For information about how to set model attribute options, see Setting model object attribute options.