Genesis 36:9-10 (KJV)

9 And these are the generations of Esau the father of the Edomites in mount Seir:

10 These are the names of Esau's sons; Eliphaz the son of Adah the wife of Esau,  Reuel the son of Bashemath the wife of Esau.

‘Generations of Esau’ is followed by subsequent generations described later in the passage. This is not the very first of the generations (Adam was) so Esau is not acknowledged as being ‘created,’ or given the importance  of  ‘in the day’.