-

select
  week_day
from
  course_classes
order by
  ((week_day + 2) % 7) -- where 2 is the current wday
;

 week_day
----------
        5
        5
        6
        6
        0
        0
        1
        1
        1
        1
        2
        2
        3
        3
        3
        4
        4
(17 rows)