When and why did people start worshiping Jesus as God?
Some people never have. Unitarians do not consider Jesus to be God and nor do Jehovah's Witnesses. I understand that not all Quakers do either.
Paul certainly regarded his Christ Jesus/Lord of Glory figure as something above mortal men and as a figure who had sovereignty over the earth but Paul was a monotheist and although on occasion he comes quite close to doing so he never directly equates Jesus with the Almighty. However, Paul came from the Hellenised world and we assume would have been aware of various religious concepts from Hellenised Judaism as well as from the all pervading wider Graeco-Roman society.
Likewise the much later
gospel of John, written around 100 CE, expands on the idea of Christ Jesus being above mortal men and also presents the Jesus figure as divine and other worldly who has descended to earth and is above humanity. We can therefore make an educated guess that ideas found in Paul went on to be developed within various Christian groups within the Hellenistic world and thus by the end of the first century (and post 70 CE) it was generally accepted that Christ Jesus was a divine figure of some sort. However, what that divinity entailed and how it was to be explained was open to a variety of interpretations, as my previous comments to you illustrated.
The thorny issue of the Son being
co equal with God the Father was a later development whose advocates would refer to various texts from the LXX as well as verses in the gospels, including those found in John, to support their beliefs.
To have seen me is to have seen the Father.
I and the Father are one
However, that same gospel provides verses indicating the Son's subordination to the Father and those verses, along with other texts from the LXX, were used by their opponents to make their case.
Very truly, I tell you the Son can do nothing on his own but only what he sees the Father doing
The Father is greater than I
By the end of the first century the separation of Christianity from its parent religion increased hostility towards Judaism and that partly lay with its appropriation of the Hebrew scriptures. Both Jesus and Paul had used Hebrew texts (the former in Hebrew the latter in the Greek translation) and verses in those texts had been reinterpreted to foretell the coming of Christ. The author of the gospel of Matthew had done this with the "suffering Messiah" which drew heavily on verses from Isaiah; but as the Christian religion developed in the Hellenistic world Christians became forced to find further justification for their use of texts from a religion that they now rejected.
Unsurprisingly perhaps the argument developed that the Jews had proved themselves unworthy of their own texts. Tertullian (c. 160 - c. 240) and the first Christian theologian to write in Latin weaved Paul's comments on circumcision into an argument that the practise was unnecessary because God and created an intact Adam.
As I commented earlier virtually all the ante-Nicene Church Fathers were subordinationists. Indeed Origen, a contemporary of Tertullian, shows elements of subordinationism in his writings by suggesting that the Son was eternally generated by the Father and therefore in certain senses subordinate. And of course Tertullian dabbled with Montanism.
So I ask again, do you know anything about the controversies surrounding the issue of the Nature of the Son that eventually led to Constantine convening the First Council of Nicaea? Do the names Arius and Alexander ring any bells with you?