Genesis 1:2 is talking about the time when God turned his attention to preparing the earth for habitation. At that time, the earth was still 'formless and waste'.
Outer space and everything in it, including planet earth, had already been in existence 'from the beginning'.
The 'creative days' spoken of in the Bible at Genesis 1:3-31- are talking about the time spent specifically preparing the EARTH for mankind.
When God first started creating things on earth, there was a 'swaddling band' or a heavy water-filled cloud all around the earth. We can see this by what happens at Genesis 1:6-8 where God seperates the cloud into water 'on the earth and water ABOVE the sky'...or 'heavens'.
So, at the time spoken of at Genesis 1:3 the thick cloud of water vapor, which had kept 'darkness on the surface of the earth', was thinning enough for light from the sun , moon and stars, to be seen from the surface of the earth. "Light came to be".
In verse 4, God sets the earth to rotating, creating night and day.
Later in vs 16, when the 'luminaries' are "made" it's important to note that the word used here is, infact, 'MADE', not 'created'. The word for MADE in Heb., wai·ya′‛as (from ‛a·sah′), is different from "create" (ba·ra'′) found in Genesis 1: 1, 21, 27 .
The Sun and moon had been 'created' LONG before, when God created the heavens. On the first "day," the expression "Let light come to be" was used. The Hebrew word there used for "light" is 'ohr, meaning light in a general sense. But on the fourth "day," the Hebrew word changes to ma·'ohr′, which refers to a luminary or source of light. (Ge 1:14) So, on the first "day" diffused light evidently penetrated the swaddling bands, but the sources of that light could not have been seen by an earthly observer. By the fourth day, things had cleared up.