Romans 5-8 speak pretty succinctly about the law being superceded by a new covenant, the curse of the law was gone. The law was in place to show us that we mankind could not on our own strength acquire or attain any standing before God on our own strength or merit. Jesus came as a man incarnate, went to the cross and we were all co crucified, co buried and co resurrected with him.

When did he die for my sins?

At the cross.

God operates outside of time and space. Adam was not a mistake and God had to clean it up. It was part of the plan of redemption. The work of the cross was mans re genesis our hard reset, a return to our redeemed innocence and original identity IN HIM.

To answer the question, did God die for all mankind. Yes, God died for all of mans sins and judged us and forgave all at the cross. But it is up to man to acknowledge and change paths.Romans 10:10 still is in tact.

License to sin, grace is not.
Titus 2:11-12
Heb 10:26
Romans 6:1-2
Ephesians 4:27
1 john 3:6-8

For it pleased the Father that in Him all the fullness should dwell, and by Him to reconcile all things to Himself, by Him, whether things on earth or things in heaven, having made peace through the blood of His cross. And you, who once were alienated and enemies in your mind by wicked works, yet now He has reconciled in the body of His flesh through death, to present you holy, and blameless, and above reproach in His sight— if indeed you continue in the faith, grounded and steadfast, and are not moved away from the hope of the gospel which you heard, which was preached to every creature under heaven, of which I, Paul, became a minister. – Colossians 1:19-23 

so Christ was offered once to bear the sins of many. To those who eagerly wait for Him He will appear a second time, apart from sin, for salvation. – Hebrews 9:28