Genesis 36:1 (KJV)

1 Now these are the generations of Esau, who is Edom.

2 Esau took his wives of the daughters of Canaan; Adah the daughter of Elon the Hittite, and Aholibamah the daughter of Anah the daughter of Zibeon the Hivite

‘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’.