II. The countdown began when "sin entered the world"
This is the beginning of God's Redemptive Plan, the count down to fully restore us back to where Adam and Eve fell from. Jesus has already given Himself (Eph.5:25, Gen.2:21) as the "last Adam" (1Cor.15:45-46) that He might present to Himself a Glorious Church, (i.e."Eve"- 2Cor.11:3, Eph.5:21-33, Gen.1:26-31) This preparation  has been ongoing since the Cross until our present day. At this present time the Church / Eve is "espoused" (engaged) as "a chasted virgin" to Christ as Mary was to Joseph. (Gen.2:22, Eph.5:21-33, 2Cor.11:2-3, Matt.1:17-25) After the marriage takes place, then the restoration will be complete and we will be back to where Adam and Eve fell from.
A. It began with the promise of the seed of the woman
God reveals His plan, that the "seed of the woman" would crush the serpents head. (Gen.3:15, Col.2:14-15, Rom.16:20, Rev.12:1-17; 13:1-3)
B. The "coats of skins"
Then God made them "coats of skins" and clothed them, (Gen.3:21) foreshadowing the Gospel. (Rom.5:12-21, Eph.2:1-22; 3:1-12) The pattern was the shedding of innocent blood (Lev.17:11, Heb.9:22) as a sacrifice to cover Adam and Eve's nakedness. (Heb.4:12-16; 9:12-26) Their "fig leaves" (i.e. our self righteousness - Isa.64:6, Rom.10:3) did not cover sin. Only the innocent, sinless blood of Christ, "who was manifest in these last times for you" (1Peter.1:18-20 / timing / plan) can take away sin. (Heb.9-10)