Hi @guinevere ,
You can use similar approach that is used in this community post answer:
Only, you need to use measure “Issues created” instead of “Issues last updated”:
CASE WHEN ([Measures].[Issues created], [Time].CurrentHierarchy.DefaultMember) > 0
THEN
Tail(
Filter(
[Time].CurrentHierarchy.Levels("Day").Members,
[Measures].[Issues created] > 0
)).Item(0).StartDate
END