If you are using the dayofweek function, do the following:
dayofweek({table.date},2)
This makes Monday the first day of the week, and the formula will return a 1 for Monday, 2 for Tuesday, etc.
You can group on this to get the correct order, but then delete the group name from the group header and use the following for display:
weekdayname(dayofweek({table.date},2),false,2) //where the false indicates no abbreviation of the weekdayname, and the 2 again designates the beginning day of the week, in this case Monday.
-LB