Nothing wrong with believing, but if you find that the Bible does not allow for your reasoning to be true, you MUST believe what the Bible tells you. The Bible was written so that each of us can go to the Bible for answers. You cannot trust what any man says, because men have a tendency to change things, just a little, but God has promised to protect His words from every generation, Psalms 12:6,7.
So, let us reason on this problem, as to what the. Bile says.
The Bible says that Jesus was God’s first Creation, Colossians 1:15. Consider also, what verse 16 says, that all things in heaven and on earth were created through Jesus, and for Jesus. The same idea is in other places in the Scriptures, Revelation 3:14, Hebrews 1:2. Now, just reason on what you have just read. The first creation was Jesus, and through Jesus and for Jesus, God Created all other things in heaven and on earth.
So, if God was going to Create Mankind, Jesus HAD to have been in existence, because before Mankind was Created, many Angels were Created, by God, with the help of Jesus, because ALL things were created through Jesus and FOR, Jesus.
The truth is, there is no telling how many eons of time went past before God started The Creations on earth. The Angels were Created before Mankind, and the Angels helped in Creation also
Many people believe that God Created all things just as we see them, but the truth is God Created matter and Jesus, acting as the Word-of God told the Angels what God wanted, and they all went to work, Psalms 33:6,9,20,21. After all, God did not make Angels to just watch as God did all the work, and clap for Him. Every intelligent being needs work for their well being. Angels work, Jesus works, God Works, John 5:17.