Question: During creation week, the moon was created on the 4th day. The first Sabbath was on the 7th day, three days after the moon was created. That means there was not time for a luni-solar seven-day cycle which would bring the moon into the correct phase to beacon the first seventh-day Sabbath. Don’t you agree?
Answer: If you use this approach that there was not time for a luni-solar seven-day cycle before the first Sabbath, then you must also apply this same principle to everything that was created. We know from Scripture that everything Yahuwah created was created in its fully mature, and “advanced upon” state, and not as seeds, eggs or babies. This would hold true for the sun, and moon as well. Scripture states that on the 4th day Yahuwah appointed, and advanced upon the placement of the sun, moon and stars. Like setting a clock, He appointed them for their specific work of measuring time. Genesis 1:14-18
"He appointed the moon for seasons: the sun knoweth his going down." -Psalms 104:19 (KJV)