When did God plan the whole scheme of things and the human experience?

God pre-planned the entire scheme of things and the human experience long before the universe was ever created. The plan of redemption was already in place before Adam was created. God was not caught by surprise; it was prophesied according to the Scriptures.

Les explains that in I Corinthians 15:3-4, Paul says he received the message that Christ died for our sins, was buried, and rose again the third day according to the Scriptures. This was not an afterthought: long before the universe was created, God had already laid out the whole scheme of things and the plan of redemption. The human experience was pre-planned before Adam was created, so God was never caught by surprise. All man has to do for salvation is believe it.

Was God caught by surprise by human history, or did He plan it beforehand?

God was not caught by surprise. Scripture indicates the whole scheme of things was laid out long before the universe was created, and the whole human experience was pre-planned. The plan of redemption was already in place long before Adam was created, with Christ's death, burial, and resurrection according to the Scriptures.