"The Hebrew word rendered “make” in Genesis 1 verse 16 is not the same as the word for “create” used in Genesis 1:1, 21, 27 chapter 1, verses 1, 21, and 27. “The heavens” that included the luminaries were created long before the “first day” even began. But their light did not reach the surface of the earth. On the first day, “there came to be light” because diffused light penetrated the cloud layers and became visible on the earth. The rotating earth thus began to have alternating day and night. (Genesis 1:1-3, 5) The sources of that light still remained invisible from the earth. During the fourth creative period, however, a notable change took place. The sun, the moon, and the stars were now made “to shine upon the earth.” (Genesis 1:17) “God proceeded to make” them in that they could now be seen from the earth." (Highlights From the Book of Genesis; w04 1/1 p. 28-p. 31; Watchtower Online Library)
"The divine will concerning luminaries was accomplished on Day Four, it being stated: “God proceeded to make the two great luminaries, the greater luminary for dominating the day and the lesser luminary for dominating the night, and also the stars. Thus God put them in the expanse of the heavens to shine upon the earth, and to dominate by day and by night and to make a division between the light and the darkness.” (Ge 1:16-18) In view of the description of these luminaries, the greater luminary was quite apparently the sun and the lesser luminary the moon, though the sun and moon are not specifically named in the Bible until after its account of the Flood of Noah’s day.—Ge 15:12; 37:9.
"Previously, on the first “day,” the expression “Let light come to be” was used. The Hebrew word there used for “light” is ʼohr, meaning light in a general sense. But on the fourth “day,” the Hebrew word changes to ma·ʼohr′, 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. Now, on the fourth “day,” things evidently changed.
"It is also noteworthy that at Genesis 1:16 the Hebrew verb ba·raʼ′, meaning “create,” is not used. Instead, the Hebrew verb ʽa·sah′, meaning “make,” is employed. Since the sun, moon, and stars are included in “the heavens” mentioned in Genesis 1:1, they were created long before Day Four. On the fourth day God proceeded to “make” these celestial bodies occupy a new relationship toward earth’s surface and the expanse above it. When it is said, “God put them in the expanse of the heavens to shine upon the earth,” this would indicate that they now became discernible from the surface of the earth, as though they were in the expanse. Also, the luminaries were to “serve as signs and for seasons and for days and years,” thus later providing guidance for man in various ways.—Ge 1:14." (Creation; Insight-1 pp. 526-547; Watchtower Online Library)
"It should be noted that, whereas Genesis 1:1 states that God “created” (Heb., ba·raʼ′) the heavens and the earth in the beginning, verses 16 and 17 state that, during the fourth creative “day,” “God proceeded to make [Heb., a form of ʽa·sah′] the two great luminaries, the greater luminary for dominating the day and the lesser luminary for dominating the night, and also the stars. Thus God put them in the expanse of the heavens to shine upon the earth.” The Hebrew word ʽa·sah′, often translated “make,” can mean simply to establish (2Sa 7:11), appoint (De 15:1), form (Jer 18:4), or prepare (Ge 21:8).
"Thus the record here states what the already existing sun, moon, and stars now became in relation to planet Earth. On the first “day” light (Heb., ʼohr) evidently gradually penetrated the cloud layers still enveloping the earth and would have become visible to an earthly observer, had he been present. (Ge 1:3) On the fourth “day” things changed." (Luminary; Insight-2 p. 284; Watchtower Online Library)