It is said that Valinor was not the original home of the Valar and that they created it in the western hemisphere of Middle Earth, but it was not their first home. What was the original dwelling place of the Valar before Melkor scorched Arda with the light of the Two Lamps?
Their first home was the Timeless Halls, out in the Void, where Eru dwells. That's where they were created, and where they lived before the Music of the Ainur. But I don't think that's what the question is asking.
Probably more in line with your thoughts is where they lived after entering into Eä. That would be the island of Almaren, where the light of the Lamps mingled (emphasis mine):
Then the seeds that Yavanna had sown began swiftly to sprout and to burgeon, and there arose a multitude of growing things great and small, mosses and grasses and great ferns, and trees whose tops were crowned with cloud as they were living mountains, but whose feet were wrapped in a green twilight. And beasts came forth and dwelt in the grassy plains, or in the rivers and the lakes, or walked in the shadows of the woods. As yet no flower had bloomed nor any bird had sung, for these things waited still their time in the bosom of Yavanna; but wealth there was of her imagining, and nowhere more rich than in the midmost parts of the Earth, where the light of both the Lamps met and blended. And there upon the Isle of Almaren in the Great Lake was the first dwelling of the Valar when all things were young, and new-made green was yet a marvel in the eyes of the makers; and they were long content.
The Silmarillion III Quenta Silmarillion Chapter 1: "Of The Beginning of Days"
Slightly more description is given in the Annals of Aman, where we learn (for example) that it was a central continent:
[T]he Valar made their dwelling upon a green isle in the midst of a lake; and that lake was between [the Two Lamps] in the midmost of Arda; and there in the Isle of Almaren, because of the blending of the lights, all things were richest in growth and fairest of hue. But the Valar were seldom there gathered in company, for ever they would fare abroad in Arda, each in his own business.
History of Middle-earth X Morgoth's Ring Part Two: "The Annals of Aman"
Almaren itself was destroyed when Melkor toppled the Lamps.