According to LDS, on what earth did God live before he became God and created everything?

A problem with this question is that you do not specify what God is being spoken of here (as having once lived as a man on some planet somewhere).

A second problem is that this quote by Joseph Smith - "that God himself, the Father of us all, dwelt on an earth, the same as Jesus Christ himself did" - identifies two different gods because they say Jesus Christ is a created creature who became a god, a different god to their idea of God the Father. But because mention is made of "the Father of us all" it's important to see from LDS doctrine who they say this Father of us all is.

As far as I can gather from the official LDS website links here, this is what they believe: https://www.lds.org/scriptures/gs/god-godhead?lang=eng&letter=g
Father in Heaven is the Father of the spirits of all mankind. Jesus is his Only Begotten Son in the flesh.

God the Son is the God known as Jehovah [in the O.T.] and is the Son, Jesus Christ… he is the eldest of the spirit children of Elohim [who is not the same deity as the one known in the Bible as Jehovah]… it was actually Jesus who was the Creator under the direction of God the Father [Elohim].

Jehovah: https://www.lds.org/scriptures/gs/jehovah?lang=eng&letter=j
Jehovah is said to be the premortal Jesus Christ and came to earth as a son of Mary (Mosiah 3:8; 15:1; 3 Ne. 15:1–5).

Michael the Archangel: https://www.lds.org/scriptures/gs/michael?lang=eng&letter=m
The name by which Adam was known in the premortal life. He is called the Archangel.

Adam: https://www.lds.org/scriptures/gs/adam?lang=eng&letter=a
Adam is the Ancient of Days and is also known as Michael (Dan. 7; D&C 27:11; 107:53–54; 116; 138:38). He is the Archangel and will come again to the earth as the patriarch of the human family, preparatory to the second coming of Jesus Christ (D&C 29:26).

They seem to teach that it was Michael who was put on earth as Adam, and Michael was one of three gods who created this planet. Adam is said to be the incarnation of a god who is ‘related’ to man. Brigham Young said on April 9, 1852:

“When our father Adam came into the Garden of Eden, he came into it with a celestial body, and brought Eve, one of his wives, with him. He helped to make and organize this world. He is Michael, the Archangel, the Ancient of Days about whom holy men have spoken – He is our Father and our God, and the only God with whom we have to do… the earth was organized by three distinct characters, namely Elohim, Jehovah and Michael, these three forming a quorum…” (Journal of Discourses 1:50-51).

This is confusing, because Adam is being called "our Father and our God".

I suggest that only after all the confusion about the various gods of the LDS religion has been cleared up can any progress be made as to answering your question. At the moment, we need to know which god was supposed to have lived on another earth-like planet somewhere else, as a man.

I will end with my encounter with three LDS men who had come to visit a friend of mine, in her house. The two American missionaries' superior claimed that Jesus created everything in this universe, in an attempt to agree with orthodox Christian doctrine, based on John 1:1-3 which I had quoted. He agreed that John 1:3 says that the pre-human Christ is stated to have made everything that was made. I pointed out that that meant he could not have been made himself. Cue startled looks on three faces. I then suggested that this contradicted Mormon theology because Mormons claim that Jesus was the firstborn spirit son of the god Elohim and his wife, and that Lucifer was one of myriad other spirit babies born to this couple, making Jesus and Lucifer brothers. "So, how come you say Jesus created everything if he and Lucifer were brothers?" Cue panic-stricken looks on the three same faces.

I suggest that investigation about this god Elohim needs to be made, and then comparison made with LDS claims about the pre-mortal Jesus creating everything. Until it's clear what god the LDS religion is speaking of, orthodox Christians will assume it's God the Father as per our Trinity doctrine, but the LDSs have a different god as their 'God the Father' - apparently it is Adam who is our Father and our God, and the only God with whom we have to do.

There is no official LDS doctrine on what earth God lived on. The LDS believe in continuing revelation so this may be revealed at a later time.

There are plenty of questions that we currently don't have the answer to, but IMO those questions aren't pertinent to one's salvation and so don't matter currently.

1 Nephi 11:17

17 And I said unto him: I know that he loveth his children; nevertheless, I do not know the meaning of all things.

See also You Know Enough, Elder Neil L Anderson

related SE post on exaltation please read this post to gain better context of below

Opinion:

From OP post

...he was once a man like us...

God has a god of his own, just like we have a God who created worlds, and we can also become gods(but do not replace God). God's god is NOT worshipped by mankind. His worlds are his own/separate.

Think of it as a family. You can become a father(god), you have a father(God), and your father has a father(his god). Your father's father is not your father, just as you becoming a father(exaltation) does not replace/reduce your father.