Was Jesus present at the beginning of time? Is there any indication in the Bible about when the Trinity came into being? Or, put another way, whether Jesus existed at the beginning?
Did the Trinity exist at the creation?
From a Christian Evangelical perspective, the answer to three of your questions is yes, and the answer to one of your questions is no.
Was Jesus present at the beginning of time?
John 1:1-2: "In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God."
Jesus (again, according to Evangelical theology) did not have a beginning; rather, He already existed at the beginning of His creative work in bringing the material universe into being.
"All things came into being through Him, and apart from Him nothing came into being that has come into being" (John 1:3).
Is there any indication in the Bible about when the Trinity came into being?
"Before the mountains were brought forth , or ever thou hadst formed the earth and the world, even from everlasting to everlasting, thou art God" (Psalm 90:2 KJV).
Since John 1:1 asserts Jesus' Deity, then Psalm 90:2 asserts, albeit indirectly, that the God of the Old Testament (Tanakh) and Jesus, the Word, are one and the same. What about the Holy Spirit, the third member of the triune God?
Well, we have Genesis 1:2:
". . . and the Spirit of God was moving over the surface of the waters."
And then there is Genesis 1:26:
"Then God said, 'Let Us make man in Our Image, according to Our likeness; and let them rule . . .."
If Jesus already existed prior to His creative work as described in Genesis; if God refers to Himself in the plural "Us"; and if Jesus is equal to God; then we needn't take an unwarranted leap of faith in saying the Trinity existed forever, and it had no beginning.
Or, put another way, whether Jesus existed at the beginning?
Yes. As John 1:1 indicates, Jesus already existed "in the beginning," prior to the first creative fiat of God; namely,
"Let there be light. . ." (Genesis 1:3, 6, 9, 11, 14, 24, and 26).
Notice, too, that in Jesus
". . . was life, and the life was the Light of men. The Light shines in the darkness, and the darkness did not comprehend it" (John 1:4-5).
We are also told in Scripture that
". . . our Lord Jesus Christ . . . will . . . [appear] at the proper time--He who is the blessed and only Sovereign, the King of kings and Lord of lords, who alone possesses immortality and dwells in unapproachable light, whom no man has seen or can see. To Him be honor and eternal dominion ! Amen" (1 Timothy 6:15-16, my emphasis).
By the way, the Light of which John speaks in John 1:4-5 is not the unapproachable light of which Paul speaks; no, the former light was the invisible made visible through the God-Man Jesus Christ. John said in the same chapter,
"There was the true Light which, coming into the world, enlightens every man" (1:9, my emphasis).
That Light, John tells us,
". . . became flesh, and dwelt among us , and we saw His glory, glory as of the only begotten from the Father, full of grace and truth" (1:14).
Did the trinity exist at the creation?
Yes. Father, Son, and Holy Spirit were all involved in the creation of all things, both immaterial and material.
Your question actually has two answers, depending on which Jesus you are referring to. We must first take into account that Jesus is both totally man and at the same time totally God. In order to give you the true answer to your question it must first be established which identity you are asking about.
It is commonly accepted among all Christian faiths; that Jesus came down from Heaven and assumed human form, Jesus himself indicated this in:
John 3:13 KJV And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
Jesus the man was born in approximately 6 BC. Jesus the man was just as you and I having the same five senses that we share. As an infant He cried just as any other baby and felt hunger, and fatigue, and all the other things any human would experience.
It is also generally accepted among all Christian faiths that That a form of Deity also resided in that human body, and that that human body came from the Holy Spirit coming upon a virgin Jewish girl named Mary.
Luke 1:26 through 35 KJV
And in the sixth month the angel Gabriel was sent from God unto a city of Galilee, named Nazareth, To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. And the angel came in unto her, and said, Hail, thou that art highly favoured, the Lord is with thee: blessed art thou among women. And when she saw him, she was troubled at his saying, and cast in her mind what manner of salutation this should be. And the angel said unto her, Fear not, Mary: for thou hast found favour with God. And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end. Then said Mary unto the angel, How shall this be, seeing I know not a man? And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
From this point on many differing points of view come into play, Some Denominations believe that the Divinity was present in the body of Jesus from the time of conception until returning to Heaven after the resurrection, Some believe that the divinity only came down from Heaven, and entered Jesus physical body at his baptism.
Matthew 3:16 KJV And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him:
Still others believe that the Deity which inhabits the physical body of Jesus is God himself. Not all Christian faiths subscribe to the concept of the Trinity, and believe Jesus, God the father and the Holy Spirit are one individual who assumes whatever form it needs at the time.
Deuteronomy 6:4 KJV Hear, O Israel: The LORD our God is one LORD:
As far as was Jesus around at the Creation Whichever, of these beliefs you subscribe to it is incumbent that all believe that God in whatever form, is eternal. That is without beginning or end. In Eternity there is no such thing as time, there is only the presence.
So the answer to your other question is that the Trinity has neither beginning nor end, but is constant.
The question of whether the Trinity pre-exists creation is dealt with as a doctrine in various Christian traditions.
You can get answers from teachings of several major streams of Christian faith, including Catholic, Eastern Orthodox, Lutheran, Reformed (sometimes called Calvinist), and Anglican among others. You'll see subtle yet important differences between them, but they basically answer your question with a yes.
You will get even wider diversity if you consult Unitarians, Jehovah's Witnesses, and Latter Day Saints (sometimes called Mormons).
There is a second doctrinal question you didn't mention by name, but is relevant here. It's the doctrine of Incarnation, God made flesh. If you think of Jesus as God made flesh, this is widely taught as happening when Jesus was conceived inside Mary's womb, long after creation.
Some people use the term Jesus to refer to the incarnate deity, and the term Christ to refer to the pre-existing member of the trinity. Others, including myself, use the two terms interchangeably.
If you want to read scripture for yourself and draw your own conclusions, you can do that. Much of scripture is helpful in this regard, but particularly the opening passages of Genesis chapter 1 and John chapter 1.
Yes He was present at the beginning.
LDS Viewpoint. I will be quoting from The Pearl of Great Price:
Moses 2:26 And I, God, said unto mine Only Begotten, which was with me from the beginning: Let us make man in our image, after our likeness; and it was so. And I, God, said: Let them have dominion over the fishes of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
This clearly states that The Only Begotten, who is Jesus Christ was with God in the beginning. As for your question about the Trinity, as member of the Church of Jesus Christ of Latter-day Saints, We Believe in God, the Eternal Father, and in His Son Jesus Christ, and in the Holy Ghost as three separate beings. We do not believe that the three members of the Godhead are one being as defined in the Trinity (See The Only True God and Jesus Christ Whom He Hath Sent by Jeffrey R. Holland Of the Quorum of the Twelve Apostles).