According to Trinitarians, who is the begotten "son" in Psalm 2 and what happened on this "day"?

Psalm 2 > 6 Yet have I set my king upon my holy hill of Zion. 7 I will declare the decree: YHWH hath said unto me, Thou art my Son; this day have I **begotten** thee **Question(s) - answer as many as you are willing and able:** - ***What day was this "son" begotten?*** - ***Can we assume this "son" is Jesus?*** - ***Was this the "day" YHWH also enthroned him in v6?*** - ***Can YHWH beget Himself? Do fathers ever beget themselves?*** (If this son is Jesus and Jesus is YHWH) - ***Did Jesus beget a son?*** (If this son is NOT Jesus and Jesus is YHWH). Applicable scripture: Psalm 89 >25 Also I will set his hand over the sea, And his right hand over the rivers. 26 He shall cry to Me, ***‘You are my Father, My God,*** and the rock of my salvation.’ 27 Also I will make him ***My firstborn,** The highest of the kings of the earth.* The author of Hebrews quotes the OT psalm: >Heb1:5 For to which of the angels did He ever say: “You are My Son, Today I have begotten You”? Jesus says about himself: >Luke 22:29 and just as My Father has GRANTED ME A KINGDOM, I grant you And Daniel... >Daniel 7:14 “And to him was **given** dominion, Glory and A KINGDOM, From Strongs: >μονογενής monogenḗs, mon-og-en-ace'; from G3441 and G1096; only-born, i.e. sole:—only (begotten, child).