The following scriptures are used by the apostle John to describe the relationship between God and Jesus:  

Jesus is called the “only begotten Son” of God in John 1:18, John 3:16, 18, and 1 John 4:9. The most accurate, word-for-word translations of the Bible translate Strong’s word G3439, μονογενής or monogenēs, as “only begotten Son.” This translation is supported in the KJV, NKJV, NASB, AS, RVIC, and YLT to name a few. In the looser, paraphrased Bibles, the translators inserted their own theologies and the original thought of those scriptures is lost.

Jesus was brought into existence by the Father. Being begotten, Jesus has a beginning, whereas the scriptures tell us that the Father has no beginning. Psalms 90:2, “…from everlasting to everlasting, thou art God." 

God the Father always refers to Jesus as a son. Matthew 3:17, "And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased." Matthew 17:5, “…a voice out of the cloud, which said, This is my beloved Son, in whom I am well pleased; hear ye him." And again in Acts 13:33, "Thou art my Son, this day have I begotten thee." 

Jesus always referred to God as his father. Luke 2:49, “…“Why did you seek Me? Did you not know that I must be about My Father’s business?”  Matthew16:16,17, “Simon Peter answered and said, ‘You are the Christ, the Son of the living God.’ Jesus answered and said to him, ‘Blessed are you, Simon Bar-Jonah, for flesh and blood has not revealed this to you, but My Father who is in heaven.” Here we have scriptural proof that God and Jesus have a father/son relationship.

Since Jesus was begotten of the Father, we conclude that there was a time when Jesus did not exist and God the Father was God alone.