Why not send Jesus right after Adam has sinned?
This is one of the stupidest question if it's from a pastor. For I have heard such question from a very shallow pastor.
To answer this:
If a man knows not righteousness, how can he be in need?
If he is not in need, how can he seek after righteousness?
If he seeks not after righteousness, why the need to give him righteousness?
Why should Christ come? If the world needs not sanctification.
This is obviously asked by someone who does not wish to truly repent, but merely to admit his status of a sinner so that he is accepted in the visible church.
Now back to the question, why wasn't it so? So that we are given the mercy to truly repent. For if Salvation is given in the beginning, those who repent but not truly, shall perish, and how many would have perished including even all of us of today's generation without such lesson? Not that the ancient Saints, whom God predestined under His grace, are anything less, but we should know better today for we have the Book.