And the twenty-four ELDERS, who sit on their thrones BEFORE GOD
Immediately after John's invitation into heaven (Revelation 4:1), we see the THRONES and ELDERS (Revelation 4:4). At that time before the 'seal judgments', they had fallen down and worshiped (Revelation 5:8).
This is the last reference in the Revelation to the 24 THRONES. They have been made unnecessary by the establishment of the kingdom of our Lord. Later, in Revelation 19:4, we see the ELDERS falling down and worshipping God again, but there is no mention of the THRONES.
Notice that the focus of attention is BEFORE GOD. This is what God demands: that we do all BEFORE HIM!
fell on their faces and worshiped God,
This is the whole consuming activity of 'redeemed men' as represented by the 24 ELDERS. The apostile Paul refers to 'redeemed' as the true circumcision who worship in the Spirit of God and glory in Christ Jesus (Philippians 3:3). On earth, we have the Holy Spirit and the glory of Christ; in heaven, we worship GOD!
Notice that the tense of the verb in Revelation 4:10 is "will worship"; here, it is "worshiped" (past active) meaning it started in the past and is ongoing.
Lastly, the act of worship here in the Revelation is face downward in complete subjection and humility. This is the opposite of the way many Pentacostal churches today conduct "Praise and Worship" with hands raised and faces looking upward. This may be the difference of how it is in the 'kingdom of the world' in which we are now and the 'kingdom of the Lord' in the future. It is curious that we don't practice worship today as it will be done in the 'kingdom of our Lord'.