How long were Adam and Eve in the Garden of Eden before the fall?

Scripture does not give a number. The internal evidence points to a very short time, most likely a week to three weeks, because Adam and Eve fell before they had any children and before Eve could have conceived. Scripture does not tell us, so anyone who gives you a precise figure is guessing. But the text does give us boundaries, and when you work within them you end up with a surprisingly short window. My estimate is a week, maybe two, maybe three. Not extremely short, not long at all. Here is the reasoning. Genesis gives the order of events plainly: Adam is created, Eve is created from him and given to him as his wife, they receive the command to be fruitful and multiply, and then the serpent comes. The first child named in Scripture is Cain, and Cain is conceived after the expulsion from the Garden. Abel follows, then Seth after Abel is murdered, and only afterward does Genesis 4 mention that Adam and Eve had other sons and daughters. So every child we know of came after the fall. They fell before they had any chance to have children. That is a real constraint on the timeline, because the command to be fruitful and multiply was given before the fall, and Adam and Eve were husband and wife before the fall. So there is a window in which they were married, under a command to have children, and did not conceive. They may well have come together as husband and wife in that window; the reason no conception resulted is simply that Eve's cycle had not yet come around. You do not want Eve carrying a child, or wondering whether she is, when the devil arrives. Once you factor in that the time has to be long enough for them to settle into the Garden and into married life, and short enough that no conception occurred, you are looking at something on the order of weeks. There is a second reason to think it was early, and it has to do with Satan. There is no statement anywhere in Scripture placing the fall of the angels at some primordial moment long before the creation of man. People try to build that out of "the earth was without form and void, and darkness was upon the face of the deep," or out of Isaiah 14, but there is no definitive statement to that effect. Ask the direct question: what chapter and verse gives us not only that Satan sinned, but when he sinned? The place where Scripture actually shows him sinning is the Garden. Satan sinned essentially at the time of Adam and Eve, and he went straight after them. He did not wait. So the picture is not of a long idyllic period that eventually soured. It is of an enemy striking almost at once, before Adam and Eve had lived very long in the relationship God had given them. That does not mean they were set up to fail. Adam was a man unencumbered by the effects of sin and physical deterioration that have plagued the rest of us since. Being a creature made out of nothing, he still needed God's power for his very existence and for all his capabilities, and God did not leave him alone to face the devil. God gave him sufficient grace to resist the temptation to sin. This was the first test of man's free will, and a test is exactly what it was: a genuine choice, with real help given. When Adam, through Eve, chose wrongly, the guilt was really his. So: a matter of weeks, most likely, and I would not bet the farm on the number. What I would insist on is the shape of it. The period in Eden was brief. Their relationship with God had not yet been deepened by long obedience. Satan struck early, precisely because he wanted to strike before they were settled. And the whole thing turned not on how long they had been there but on whether they would take God at His word when someone told them He was lying.