The Lord’s Day begins the day that Jesus returns, and this entire time period is generally called the Lord’s Day (the Day of the Lord is mentioned throughout the major and minor prophets). However, as we are told, a day with the Lord is as a thousand years for man (2Pet 3:8), so not only does the Day of the Lord consist of the day He returns (Rev 1:4-11), but lasts for the entire Millennium. The Millennium is known as the Lord’s Day.
If we look at the time since Adam was made, which was approximately 6000 years ago, as a week symbolically, then what we see is that the Millennium, which will be a thousand years itself, would make of the 7th day of the week, the Lord’s Day. This is a 7000 year span lasting from the formation of Adam by God to the end of the Millennium, with each thousand-year period being as one day in the Lord’s eyes.
Now, 7 is a number, which in the Bible represents spiritual completion, so this tells us that at the end of the Millennium, we will finally reach a stage, after satan is released one last time, in which, those who have not been destroyed in the Lake of Fire (Rev 20:10-15) will be spiritually complete, and all evil will have been purged from God’s Kingdom. The number 1000 represents our Father’s Glory in the Bible, and this is because after the Millennium, a time period when the Son will reign on earth in person, God will come down to earth in His full glory to rule on earth in our midst (Rev 21-22). And the number 7000, in the Bible, represents the Zadok, as well as Final Judgment. There are 7000 predestinated elect on earth in this final generation (Rom 11:4), but aside from that, at the end of this 7000 year period, from the time of the formation of Adam, will be the Final Judgment (Rev 20:11-13), which is at the end of the Millennium.
If you extend the understanding that a day with the Lord is as a thousand years with man, and apply it to the creation of this earth age, then each day in Genesis 1 would be a one-thousand-year period, but to God it was one day each. The word translated as “day” in Genesis 1, yom, does not always mean a literal day. Yom can also mean a season, a time, or an age. The term translated as evening, ereb, can also be used in a symbolic sense. Therefore, we can surmise that what we are talking about here, in Genesis 1, is six 1000-year time periods. The reason that this is significant is that the recreation of the earth in this earth age given to us in Genesis 1, and including the 7th day, the Sabbath, in Genesis 2, a one week period in God’s eyes, is a 7000-year period as well.
If we understand that man (all races) was created as hunter/gatherers on the 6th day (Gen 1:26-30), the number 6 representing man in the Bible, and Adam was created after the 7th day as the first man to till the soil (Gen 2:5-9), or farmer, then we are talking about two 7000-year periods, or 14,000 years. The number 14 in the Bible represents deliverance and salvation, and remember that we said that 1000 represents our Father’s Glory. What this tells us is that, when the Final Judgment occurs at the end of the Millennium, the Great White Throne Judgment, it is 14,000 years after God began creating this present earth age. Those who are found written in the Book of Life at that time will not be destroyed in the Lake of Fire, and thus they will have salvation and deliverance.
Bearing all that in mind, the Lord will return and the Lord’s Day will begin after the Tribulation (Matt 24:29-31, Mark 13:24-27, Luke 21:20-28). Jesus will return for His Second Coming during what is called the Battle of Armageddon, and will wipe out all of antichrist‘s forces that will be surrounding God’s Elect desiring to destroy them (Zech 14, Rev 11, 16:12-21), and this will bring in the Millennium Kingdom (Eze 40-48, Rev 21).