These following scriptures have been rewritten, for the purpose of making them more clear unto the reader.

The Strong's Hebrew Dictionary was used, to receive a better understanding of what these scripture are showing, which are written in The King James Version Bible.

EXO 16:1  And they pulled up the tent pegs and started on a journey, out of Elim, and all the congregation of the children of Israel entered into the wilderness of Sin, which is between Elim and Sinai, 'On A Portion Of The 15th Day Before Darkness Arrived', in the second month:(lunar month), after their departing out of the land of Egypt.

This verse here show that the Children of Israel entered into the wilderness of sin, on the first part of the fifteenth day of the second lunar month, after the sunset of the 14th day, before darkness had arrived.  The first part of a day is the evening.  Remember, days begin at sunset.

EXO 16:2  And the whole congregation of the Children of Israel murmured against Moses and Aaron in the wilderness:
EXO 16:3  And the Children of Israel said unto them, would to God:(ALaHiYM) we had died by the hand of YaHuWaH in the land of Egypt, when we sat by the flesh pots, and when we did eat bread to the full;  for ye have brought us forth into this wilderness, to kill this whole assembly with hunger.
EXO 16:4  Then said YaHuWaH unto Moses, behold, I will rain bread from heaven for you;  and the people shall go out and gather a provision each day at the break of day, that I may prove them, whether they will walk in my Law, or not.
EXO 16:5  And it shall come to pass, that on the sixth day, they shall prepare what they bring in;  and it shall be twice as much as they gather daily.

These verses here show that it was upon the 15th day, when YaHuWaH talked unto Moses, about raining bread from heaven.
The 15th day was the first day of the six days, when the Children of Israel should gather the bread from YaHuWaH.  YaHuWaH told Moses these things on the 15th day after the sunset ended the 14th day.  Remember that the days began in the evening after a sunset.

EXO 16:6  And Moses and Aaron said unto all the Children of Israel, this evening as it grows dark, then ye shall know that YaHuWaH hath brought you out from the land of Egypt:
EXO 16:7  At the break of day on this same 15th day, then ye shall see the glory of YaHuWaH;  for that he heareth your complaints, which go on during this night against YaHuWaH: and what are we, that you complain this night against us?
EXO 16:8  And Moses said, this shall be, when YaHuWaH shall give, as the day grows dark, flesh to eat, and at the break of day, bread to the full;  for that YaHuWaH heareth your murmurings that ye murmur against him: and what are we?  Your murmurings are not against us, but against YaHuWaH.
EXO 16:9  And Moses spake unto Aaron, say unto all the congregation of the Children of Israel, come near in the presence of YaHuWaH: for he hath heard your murmurings.
EXO 16:10  And it came to pass, as Aaron spake unto the whole congregation of the Children of Israel, that they looked toward the wilderness, and behold, the glory of YaHuWaH appeared in the cloud.
EXO 16:11  And YaHuWaH spake unto Moses, saying,
EXO 16:12  I have heard the murmurings of the Children of Israel: speak unto them, saying, as it grows dark this evening, ye shall eat flesh, and at the break of day, ye shall be filled with bread;  and ye shall have respect for we, who are YaHuWaH ALaHiYM.

The Hebrew word 'ALaHiYM' is a plural word, which means Mighty Ones .  ALaHiYM are YaHuWaH:(Self Existent and Continual) ALaHiYM:(Mighty Ones).

EXO 16:13  And it came to pass, as it grew dark, the quails came up and covered the camp, and at the break of day the dew lay round about the host:(encampment).
EXO 16:14  And when the dew that lay was gone up, behold, upon the face of the wilderness there lay a small round thing, as small as the hoar frost on the ground.
EXO 16:15  And when the Children of Israel saw it, they said one to another, it is manna: for knowing not what it was.  And Moses said unto them, this is the bread, which YaHuWaH hath given you to eat.
EXO 16:16  This is the thing, which YaHuWaH hath commanded, gather of it, every man, according to his eating, an omer for every man, according to the Number of your persons;  take ye every man for them, who are in his tents.
EXO 16:17  And the Children of Israel did so, and gathered, some more, some less.
EXO 16:18  And when they did mete it with an omer, he, who gathered much, had nothing over, and he, who gathered little, had no lack;  they gathered every man according to his eating.
EXO 16:19  And Moses said, let no man leave of it past the break of day.
EXO 16:20  Notwithstanding, they hearkened not unto Moses;  but some of them left of it past the break of day, and it bred worms, and stank: and Moses was wroth with them.
EXO 16:21  And they gathered it morning by morning at the break of day, every man according to his eating: and when the sun waxed hot, it melted.
EXO 16:22  And it came to pass, that on the sixth day they gathered twice as much bread, two omers for one man: and all the masters of the congregation came and told Moses.
EXO 16:23  And he said unto them, this is what YaHuWaH hath said, to morrow is the rest of the Holy Sabbath unto YaHuWaH: cook namely what you cook, boil what you boil;  whatsoever remains over and above, let alone and let stay, keep it past the break of day.

In EXO 16:23 up above, it is NOT written that man must NOT do any cooking on the Sabbath day.  It does not imply that.  Remember, the priest of YaHuWaH were commanded to sacrifice animals every day, as a burnt offering unto YaHuWaH ALaHiYM, which also included all Sabbaths.  Also, they baked fresh Bread to be laid out on the table of showbread, every Seventh Day Sabbath.

EXO 16:24  And they laid it up till the morning, as Moses bade: and it did not stink, neither was there any worm therein.
EXO 16:25  And Moses said, Eat that To Day;  for To Day is A Sabbath unto YaHuWaH: To Day ye shall not find it in the field.
EXO 16:26  Six Days you are to pick up, to gather it;  but on The Seventh Day, which is The Sabbath, in it there shall be none.
EXO 16:27  And it came to pass, that there went out some of the people on The Seventh Day to pick up, to gather, and they found none.
EXO 16:28  And YaHuWaH said unto Moses, How long refuse ye, to keep the Commandments of the Law?
EXO 16:29  See, for that YaHuWaH hath given you the Sabbath, therefore He giveth you on the sixth Day the bread of two Days;  abide ye every man in his place, Let No Man Go Out Of His Place On The Seventh Day.
EXO 16:30  So the people rested on The Sabbath:(Seventh Day Sabbath).

What these verses are implying, up above:

Gather your food on the sixth workday, before 'the seventh day' come, which is the Sabbath Day.
Moreover, this is what the Children of Israel were commanded to do, before the passover lambs were sacrificed on the Seventh Day Sabbath, the 14th of Abib lunar month, at the going of the sun.  They were commanded to fetch and, or to buy upon the 10th of Abib lunar month.  They did not go out and fetch them upon the Seventh Day Sabbath.

EXO 16:31  And the house of Israel called the name thereof Manna: and it was like coriander seed, white;  and the taste of it was like wafers made with honey.

From the above account, it can be ascertained that on the 15th day of the second lunar month, after the sun had set, which ended the 14th day of the second lunar month, the Children of Israel began their journey out of Elim, and entered into the wilderness of Sin, during the year of the exodus from Egypt.  This journey occurred on the 15th day of the second lunar month, just after a Seventh Day Sabbath.  That Seventh Day Sabbath existed upon the 14th day of the second lunar month.

YaHuWaH ALaHiYM sent them manna for six days, starting on the 15th day of the second lunar month at the break of day.  When the next seventh day:(Seventh Day Sabbath) came, it came upon the 21st day of the second lunar month.

Conclusion:
The Seventh Day Sabbath come upon the 14th day and 21st day of the second lunar month.  Moreover, the Seventh Day Sabbath come upon the 7th day of the second lunar month, which comes seven days previous to the 14th day, and also upon the 28th day of the second lunar month, which comes seven days after the 21st day of the second lunar month.

This agrees with the Babylonian archeological findings, wherein, the 7th, 14th, 21st, and 28th days are 'Seventh Day Sabbaths'.  Moreover, it supports The Lunar Month Sabbath Doctrine, which we find here in the scriptural account of the second lunar month after the exodus, which include Seventh Day Sabbaths of the 7th, 14th, 21st, and 28th days of the second lunar month.

To Understand How To Count Unto The Feast Of Firstfruits, From The 15th Day Of Abib Lunar Month, Using The True Lunar Calendar, Click On This Link:  Counting Unto the Feast of Firstfruits, From the Morrow After the Seventh Day Sabbath