In Genesis 1:28, God commanded Adam and Eve to be fruitful and multiply. If they had waited very long, they would have been sinning against God by not being fruitful. Also, since they were created with perfect bodies, it would not have taken long for Eve to conceive. So, the time between the Creation and the Fall must have been short.
Some people have said that the Fall could not have occurred so early because Adam walked with God in the Garden and this suggests an intimate relationship between Adam and His Creator that could only be developed over time. However, the Bible never says that Adam walked with God in the Garden. Although many people have taught this, it is not found in Scripture. Adam and Eve were hiding because of their sin when they heard the sound of the Lord God walking in the Garden (Genesis 3:8), and note that this is after sin.
In Genesis 3 , Adam and Eve sinned (in part due to Satan’s actions) and were kicked out of the Garden of Eden. According to Scripture, this happened prior to conceiving their first child, Cain (Genesis 4:1).
Genesis 5:3 indicates that Adam had Seth at age 130 and Genesis 4:25 indicates this took place after Cain killed Abel. Adam had at least three children before Seth: Cain (Genesis 4:1), Cain’s wife1 (Genesis 4:17), and Abel (Genesis 4:2). Since Cain and Abel were old enough to work with crops and herds, respectively, the maximum time before the Fall would have to be much less than 130 years.
Looking back at the Creation Week, Adam and Eve couldn’t have sinned on Day 6 (the day Adam and the Woman were created), since God declared that everything was “very good.” Otherwise, sin would be very good. Day 7 is also unlikely, since God sanctified that day. Therefore, the Fall likely happened soon after this.
Archbishop Ussher suggests that Adam sinned on the tenth day of the first month in Ussher’s chronology, which is the Day of Atonement.2 The Day of Atonement presumably represents the first sacrifice, which God made by killing animals (from which He made coats of skins in Genesis 3:21) to cover Adam and Eve’s sin.
Ussher’s reasons for choosing this date make sense. However, we can’t be certain of the exact date or length of time prior to the Fall beyond the points established above.