‘And the twenty four elders who sat before God on their thrones fell on their faces and worshipped God, saying, “We give thanks Oh Lord God, the Almighty, who is and who was, because you have taken your great power and enforced your reign (reigned - aorist ingressive)”.'
We note that there is no longer a mention of ‘is to come' (Revelation 1:8; Revelation 4:8) for He has come, and it is now the end of time. He has taken His great power and enforced His reign. He has of course previously been reigning in Heaven and in the hearts of His people. Now His reign over mankind as a whole is enforced, expressed in His final acts of judgment. The twenty four elders may well worship. Their task is complete and the redeemed church is in Heaven.