This is very interesting, so are you saying that Eve did have lust of the eyes before she ate the fruit, so sin was present before the actual act of disobeying God's command?
When you take this along with His teaching on what murder is - that we have already done it, already done it! - when we have anger at our brother, this makes you see that it is not something you can do, to not sin. It's impossible for you, because the sin is IN YOU.
As a man thinks in his heart, so is he. It is only men who would say Eve did not sin until she performed an outward action. She sinned when she began to doubt that God had told the truth. This unbelief is what led to all the rest. God examines the thoughts and the hearts intent. So it is only men who look only at the outside.
The sin of Eve was unbelief.
Whatever is not of belief is sin.
There would only be one reason you would eat a cookie if I told you not to eat it because it had been poisoned and you would die if you ate it. The only reason you would eat it is if you truly believed that I didn't tell you the truth.
Eves sin was unbelief/mistrust about what God had said. All that happened after - the lust of her eyes, the outward disobedience - were all sprung from the sin of unbelief. If she hadn't sinned inwardly first in unbelief, none of the other things would have happened because if the inside of the cup is clean, the outside just is as well.
And here we are, trying hard to keep reading so that we will be careful with any areas of unbelief. To take care that our own hearts do not become evil and unbelieving.