How early was this sacrificial system known?

Answer

"By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he
was righteous, God testifying of his gifts." Heb. 11: 4. See Gen. 4: 3-5; 8: 20.

By what is every child known?
Was there anything made without Christ?
How much do the dead know of what is going on among men?
Whatever may come, what blessed assurance has everyone who loves God?
What does Paul say God has prepared for His people?
What is the measurement of the city?
From what ills will the saints he for ever delivered?

Questions & Answers are from the book Bible Readings for the Home Circle