The phrase often translated as Followed in the KJV is composed of the Hebrew words hayah (הָיָה) and ahar (אַחַר). It is sometimes taught by Lunar Sabbatarians that the word hayah by itself can also mean “followed”.
This page presents the rationale for why hayah should mean "followed" and discusses objections.
The word hayah, translated throughout Genesis 1 as "were" (i.e. "the evening and the morning were the first day", could also be translated as "followed". For example, in 2 Sam 2:10, Judah followed (were) David; in 1Ki 16:21, the people followed (were) Tibni. Obviously Judah was not David, and the people were not Tibni, so the correct translation of the word in these verses is indeed "followed".
So consider in Genesis 1:5 that, instead of translating hayah as "were", we translate it as "followed". We now read this passage as “… and the evening and the morning followed the first day.” This supports the fact that the heavens and the Earth were created on the day before “the first day” of Creation (on the New Moon Day), YHVH worked for six days after that, and that the Sabbath followed those six working days.
The word hayah is never translated as “followed” unless used together with the word ahar (i.e. “were behind”).
Hayah (Strong's number H1961) is a verb meaning “to exist, to be, to become, to come to pass, to be done”.
Ahar (Strong's number H310) is a preposition meaning “behind, after, afterwards”.
Used together, they could be translated as “were behind” or “were after”, i.e. “followed”.
Usage in the Bible
In Genesis 1:5, ahar is not used before hayah, it is used by itself. Therefore it is simply (and correctly) translated as “were”, and the passage reads “...and the evening and the morning were the first day.”
A good example of the usage of both Hayah and Ahar can be found in 1 Kings 16:21 :
Then were the people of Israel divided into two parts: half of the people followed (H1961+H310) Tibni the son of Ginath, to make him king; and half followed (H310) Omri.
Here the word "followed" is used twice in English. However both the words Hayah (H1961) and Ahar (H310) are used the first time while only the word Ahar (H310) is used the second time (a fact omitted in the Assertion above). Using the definitions of "were" and "behind" for Hayah and Ahar, this passage can be read as:
Then were the people of Israel divided into two parts: half of the people were behind Tibni the son of Ginath, to make him king; and half behind Omri.
In 2 Sam 2:10, both Hayah and Ahar are used:
...But the house of Judah followed (H1961+H310) David.
There are no examples in the Bible where the word "Hayah" can be used by itself to mean "followed". Therefore it is not valid to assert that Genesis 1:5 can be translated as “… and the evening and the morning followed the first day.”