Hi @nocodelife,
The best way to do this on a per user basis is to use the custom dates. The start day can be dynamic so you would store the day number for the group that their notification are being sent on and make the Start Day # conditional to that date. Then set up Custom Date 1 with a value of 0 days (this is this week’s value) and Custom Date 2 with a value of 7 days (next week’s value). Like this:
Then use Custom Date 1 with a condition that says if Custom Date 1 < Current Date/Time then use Custom Date 2.
That should do what you need!
Side note and you may have considered this but I would recommend scheduling your workflow on the group itself. Each group would have a single API Workflow scheduled for the day of the week when their notifications should be sent out. When that workflow triggers it simply loops through all of the group’s users and sends a notification to each user. This would save the need to schedule a workflow for each new user that joins.