Group by DATETIME_FORMAT 'ddd'


We’re running a slot time schedule for incoming deliveries.
To make the view optimal, the first field i group by is a “WEEKNUM” formula which works good. The second value i want to group by is the day. Before i used to group by is “WEEKDAY” but the problem is that only returns a raw number (1, 2, 3 ,4 and 5).
So i read about datetime modifiers and found that DATETIME_FORMAT ‘ddd’ was the one I’m looking for. The problem is that when i group by that the groups don’t sort in chronological order, they sort alphabetical.
I’ve read other threads where they solved it by sorting in a different field but since I’m grouping that solution don’t fit me. Or maybe I’m just missing something obvious. What I’m after is that the second group (day) displays “Mon, Tue, Wed” etc instead of “1, 2, 3”.

Thankful for any response!