These quotes are all from standard LDS sources. The LDS Collector’s Library 1997 CD ROM from Infobases was used.
Teachings of the Prophet Joseph Smith, Section Six 1843-44, p. 345
“God himself was as we are now, and is an exalted man, and sits enthrones in yonder heaves! That is the great secret. If the veil were rent today and the great God who holds this world in its orbit, and who upholds all worlds and all things by his power, was to make himself visible, –I say, if you were to see him today, you would see him like a man in form –like yourselves in all the person, image, and very form as a man; for Adam was created in the very fashion, image and likeness of God, and received instruction from, and walked, talked and conversed with him, as one man talks and communes with another.”
Teachings of the Prophet Joseph Smith, Section Six 1843-44, p. 345
“In order to understand the subject of the dead, for consolation of those who mourn for the loss of their friends, it is necessary we should understand the character anf being of God and how he came to be so; for I am going to tell you how God came to be God. We have imagined and supposed that God was God from all eternity. I will refute that idea, and take away the veil. So that you may see.”
Teachings of Lorenzo Snow, p. 5
“If there ever was a thing revealed to man perfectly, clearly, so that there could be no doubt or dubiety, this was revealed to me, and it came in these words: ‘As man now is, God once was; as God now is, man may become.’”
Bruce R. McConkie, Mormon Doctrine, p. 321 under Godhood
“Joseph Smith said: “God himself was once as we are now, and is an exalted man, and site enthrones in yonder heavens! I am going to tell you how God came to be God. We have imagined and supposed that God was God from all eternity. I will refute that idea, and take away the veil, so that you may see. It is the first principle of the gospel to know for a certainty the character of God, and to know that we may converse with him as one man converses with another, and that he was once a man like us; that God himself the Father of us all, dwelt on an earth, the same as Jesus Christ himself did; an I will show it from the Bible.”
Encyclopedia of Mormonism, Vol. 2 under Godhood
“Latter-day Saints believe that god achieved his exalted rank by progressing much as man must progress and that God is a perfected and exalted man: ‘God himself was once as we are now, and is an exalted man, and sits enthroned in yonder heavens! That is the great secret. If the veil were rent today, and the great God who holds this world in its orbit, and who upholds all worlds and all things by his power, was to make himself visible, — I say, if you were to see him today, you would see him like a man in form — like yourselves in all the person, image, and very form as a man; for Adam was created in the very fashion, image and likeness of God, and received instructions from, and walked, talked and conversed with him, as one man talks and communes with another.’ (TPJS, p. 345)
It should be evident that early LDS leaders (including Joseph Smith) believed and taught that God was once a man. The Encyclopedia of Mormonism was published in 1992 and therefore reiterated these teachings.