Any idea why all usurping nations aren't brought into Jesus' control, and he shall have put down all rule and all authority and power? Let's see, you're saying that Jesus has been working at that now for close to 2000 years?
I will try to answer most of your questions with this longish post. If you have any more questions, just ask.
Is Jesus on His throne at this time?
1. In Psalm 110, Jesus is to sit at God's right hand (v.1), He is to rule until His enemies are made His footstool (v.1), His scepter will be stretched over Zion as He rules in the midst of His enemies (v.2), the people will volunteer in the day of His power (v.3), He will be a priest during this rule (v.4), He will shatter kings and judge the nations, etc. while at God's right hand (vv.5-7).
2. In Psalm 2, Jesus is to be opposed by the rulers (vv.1-3), God in heaven scoffs at their attempts to stop His plan (vv.4-5), God sets up Jesus as King on Zion (vv.6-7), the King is given everything as His possession (v.8), the King will oppose His enemies with a rod of iron (v.9), the people are encouraged to worship the King and to take refuge in Him (vv.10-12).
3. Acts 2:22-36 and 4:24-28 and Hebrews 1:5 & 13 all quote from these two Psalms to describe their having already been fulfilled in Christ.
4. In Psalm 16:8-11, David prophesies of his descendant who will be resurrected to sit on his throne, in fulfillment of the prophecy given in 2 Samuel 7:12-17, according to Peter in Acts 2:22-36. Peter is clear that Jesus has fulfilled these prophecies by His resurrection and ascension to the throne of David. Jesus now exercises that authority over the people of God as King and High Priest.
5. If Christ is presently High Priest, and He is, then He is now seated on David's throne over His kingdom as prophesied and promised. Even Zechariah 6:12-13 describes the fact that the Messiah will rule on the throne in the capacity of both King and Priest. Christ's throne and His priesthood go together and are inseparable.
6. In 1 Corinthians 15:23-28, Christ is to rule until His enemies are made a footstool for His feet. The last enemy is death. When He has abolished all of His enemies, He will deliver the kingdom to God in heaven. Compare your Hebrews 2:8 reference to 1 Corinthians 15:23-28. Christ is currently ruling with all authority. The last enemy to be subjected is death. When He has subjected death and the resurrection of all takes place, then it is the end and He will subject Himself to the One who gave Him all rule and authority.
We have a promise to sit the Messiah on the throne of David, we have David anticipating this and writing of the resurrection of the Messiah and His consequent rule from heaven until His enemies are all conquered, and we have Paul writing that Jesus will reign until His enemies are all conquered at which time He will return to deliver the kingdom up to the Father.
If you acknowledge Jesus is now High Priest, and if you acknowledge that He is now at the right hand of God, then you have to accept the rest of what the Psalms are saying about Him and His rule.
Part of the problem may be with understanding what is meant by the word “throne.” Is it supposed to be defined as a physical chair? No, the throne is a term that refers to the authority over the kingdom. Compare this to Matthew 23:1. The scribes and the Pharisees have seated themselves in the chair of Moses. Jesus was not referring to a physical chair, but rather to that position of authority.
Jesus does not have to be described as “sitting” in order to be described as King on His throne. He can be described as standing, walking, whatever. The point is that He has the authority as King and Priest. As High Priest He mediates and as King He rules. Jesus has been doing these since His resurrection and ascension into heaven.