The section in the book of Revelation known as the "seven seals" (Rev 4:1 - 8:1) also contains the "seven hymns" as follows:
- Rev 4:8 - 4 living creatures sing to God:
Holy, holy, holy is the Lord God Almighty, who was, and is, and is to
- Rev 4:11 - 24 elders sing to God:
You are worthy, our Lord and God, to receive glory and honour and
power, for you created all things, and by your will they were created
and have their being.
- Rev 5:9, 10 - 4 living creatures and 24 elders sing to the Lamb:
You are worthy to take the scroll and to open its seals, because you
were slain, and with your blood you purchased men for God from every
tribe and language and people and nation. You have made them to be a
kingdom and priests to serve our God, and they will reign on the earth.
- Rev 5:12 - Many angels +  living creatures +  elders sing to the Lamb:
Worthy is the Lamb, who was slain, to receive power and wealth and
wisdom and strength and honour and glory and praise!
- Rev 5:13 - "All Creatures" sing to God and the Lamb:
To him who sits on the throne and to the Lamb be praise and honour and
glory and power, for ever and ever!
- Rev 7:10 - Great multitude in white robes sing to God and Lamb:
Salvation belongs to our God, who sits on the throne, and to the Lamb.
- Rev 7:12 - All angels, elders and 4 living creatures sing to God:
Amen! Praise and glory and wisdom and thanks and honour and power and
strength be to our God for ever and ever. Amen!
Note that the greatest number sing in hymn number 5 (Rev 5:13) - those that sing are described as:
every creature in heaven and on earth and under the earth and on the
sea, and all that is in them.
This is clearly a Hebraism describing all creation in the phraseology of Ex 20:11. This is often quoted elsewhere such as: Ps 69:34, 146:6, Acts 4:24, 14:15, Rev 10:6, 12:12, etc. John 1:1-3 also alludes to this as well plus Col 1:16.
Thus, this fifth hymn in Rev 5:13 praises God and the Lamb as creator of all things and is sung by all created beings. The next hymn praises God and Lamb providing salvation. Thus, God and the Lamb are praised as creators and re-creators.
The timing of the enthronement ceremony of the Lamb, I believe is rather simple. Note that Rev 4 presents a scene of continuous worship of God which grinds to a halt when John sees the vacancy on the throne beside God, on the right side! This is filled by Jesus as the slain Lamb (Rev 5:6).
Thus we find Jesus taking His seat on the heavenly throne as the ruling monarch (ἐπὶ τὴν δεξιὰν = on the right). This is alluded to frequently in the NT such as: Matt 26:64, Mark 14:62, 16:19, Luke 22:69, Acts 2:33, 7:55-56 (standing), Rom 8:34, Eph 1:20, Col 3:1, Heb 1:3, 8:1, 10:12, 12:2, 1 Peter 3:22. See also Ps 110:1, Matt 22:44, Mark 12:36, Acts 2:34, Heb 1:13.
Thus, I assume that Jesus, upon His assension to heaven, after His resurrection, was installed in the throne of heaven, on the right hand side and began His reign as the conquering king of the universe, Rev 11:17.
During His earthly ministry, Jesus gave anticipatory evidence of this by the following:
- He was called the king of the kingdom of Israel and the king of the kingdom of heaven, . Matt 1:1, 20, 9:27, 12:23, 15:22, 20:30, 15, 21:9, 15, Mark 10:35, Luke 1:32, 33, 18:38, 39, John 1:49, Acts 13:32-37, Heb 1:8.
- He was in complete control of the natural elements such as when He calmed the storm on the sea of Galilee.
- He healed many people of their diseases
Note especially the words of the angel to Mary before His birth as recorded in Luke 1:32, 33 -
He will be great and will be called the Son of the Most High. The Lord
God will give Him the throne of His father David, and He will reign
over the house of Jacob forever. His kingdom will never end!”
Thus, while, Jesus began to reign as the triumphant Lamb at His ascension, that reign will be only become undisputed when Jesus returns and Rev 11:17, 18 is fulfilled. We also have an almost parallel and confirming passage in Phil 2:9-11 - every knee will bow, etc.