The Doctrine of the Trinity was very late in developing, it is certainly not found in any form in the N.T that does not require a huge stretch. Its development/evolution was probably spurred on by a desire to accommodate Greek Philosophical thinking.
It was never a huge part of the early thinking of the various Jesus sects as far as I can see, not even the Gnostics.
Ideas of an incipient doctrine of the meaning of the Divinity of Jesus , as the two being "one" can maybe seen in very late works like The Gospel of John,( early 1st Century, maybe later) but again, it is a stretch to read in to the words that the Holy Spirit is Yahweh.
Were it a great truth, surely it would be unequivocally expressed in the N.T, and made a great part of the idea of how to gain " salvation" ?
I am no great enemy of the Doctrine from a philosophical point of view, and the Doctrine is nothing like the simplistic J,W explanation and " refutation" of it. As with many things, the J.W Org speaks of things of which it knows not.