PMW 2025-010 by Jame R. Hughes (Creation.com)
Gentry Note:
Creation is the foundation to all theology. This is significant for postmillennialism in that Creation leads ultimately to New Creation, and since the resurrection/ascension of Christ we are “new creations,” spiritually anticipating the consummate New Creation. Thus, the revelation of creation and the fall in Genesis is a crucial aspect of a full-fledged theological structure.This article on the timing of Adam’s sin in Eden matches what I have long thought. It is a succinct presentation of this important feature of Adam’s failure in Eden.
How long were Adam and Eve in the garden?
When I have been speaking on behalf of CMI, I have been asked a few times, “How long were Adam and Eve in the Garden of Eden?” A simple answer is to state that the Bible does not tell us the answer. However, we can draw legitimate inferences from other passages in the Bible and from what we know about current human biology which may help us provide a possible answer.
At the conclusion of the sixth day of creation, God declared all that he had made to be “very good” (Genesis 1:31). Since there was no sin in the perfect state at the end of that day, Adam and Eve were not expelled from the garden of Eden on the sixth day of creation. The events in Genesis 3—the fall of Adam and Eve into sin and their expulsion from the Garden of Eden could have occurred hypothetically on the next day, the first Sabbath—the seventh day of the creation week—or weeks or months after the first Sabbath.
However, we can probably provide a boundary condition for the duration of their tenancy in the perfect state in the garden through a consideration of contextually nearby statements in the Bible:

As It Is Written: The Genesis Account Literal or Literary?
Book by Ken Gentry
Presents the exegetical evidence for Six-day Creation and against the Framework Hypothesis. Strong presentation and rebuttal to the Framework Hypothesis, while demonstrating and defending the Six-day Creation interpretation.
See more study materials at: www.KennethGentry.com
“And God blessed them. And God said to them, “Be fruitful and multiply and fill the earth and subdue it …” (Genesis 1:28)
“Now Adam knew Eve his wife, and she conceived and bore Cain …” (Genesis 4:1)
Important inferences
We can infer the following from these verses:
➡Eve would have been fertile, and a conception would have occurred within a relatively short time after her creation.
➡ God gave Adam and Eve a command to procreate while in the perfect state in the Garden of Eden. Adam and Eve were intended to produce offspring even before sin entered the world.
➡ Adam and Eve likely had sexual intercourse at least once within the perfect state before their expulsion from the garden. They would have been fulfilling the command to be fruitful and multiply and would have experienced the God-given pleasure of connubial intercourse.
➡ Since there were not yet any consequences from the curse on sin while Adam and Eve were in the garden, Eve would have been fertile, and a conception would have occurred within a relatively short time after her creation.
Creation according to the Scriptures
Ed. by P. Andrew Sandlin
This book is sub-titled: A Presuppositional Defense of Literal , Six-day Creation. It has chapters by R. J. Rushdoony, Andrew Sandlin, Kenneth Gentry, Cornelius Van Til, and others. It touches on historical, exegetical, theological, and philosophical implications of Six-day Creation.
See more study materials at: www.KennethGentry.com
➡ The participation of Adam and Eve in sexual relations while they were in the garden must not have resulted in a conception.
➡ The first recorded conception took place after Adam and Even had sinned and been expelled from the garden of Eden.
The first recorded conception took place after Adam and Even had sinned and been expelled from the garden of Eden.
Understanding the Creation Account
DVD set by Ken Gentry
Formal conference lectures presenting important information for properly approaching the Creation Account in Genesis. Presents and defends Six-day Creation exegesis, while presenting and rebutting the Framework Hypothesis.
See more study materials at: www.KennethGentry.com
These inferences include key assumptions
➡ We must be cautious not to project observations about current biological processes into the pre-sin paradise. However, even in the prefect state, Eve probably had some form of a menstrual cycle (however without associated cramps or pain; Genesis 3:16) and a period of fertility within her ‘monthly’ cycle. A woman is fertile usually beginning with the 7th or 8th day after the commencement of her menstrual cycle. This may have also been the situation for Eve….
To finish reading article, go to: https://creation.com/adam-and-eves-tenancy-in-the-garden-of-eden

If this is accurate, then being expelled from the garden on day 8 would coincide with the idea that the number eight is associated with resurrection and pair very well with the book of Revelation and Paradise restored.
This could well be the case.