The word "homosexual" is something of a monstrosity, like the word "television"--it combines a Greek root with a Latin root. The Modern Greek word for "homosexual" is omophylophilos, combining the roots for "same," "sex" and "friend."
The Bible became anti-gay whenever the story of Lot or the laws of Moses were written down, whichever was earlier.
It was actually anti-gay from the beginning when God created Adam and Eve. So it goes way back to the beginning.