hi all---------
1Co 15:3 For I give over to you among the first what also I accepted, that Christ died for our sins according to the scriptures,
1Co 15:4 and that He was entombed, and that He has been roused the third day according to the scriptures,
Mat 12:40 For as Jonah was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth.
If I understand this correctly,the three days start at the point of the betrayal in the garden by judas.The heart of the earth(man is made of the dust of the earth) refers not to the tomb(though some of the time was spent there)but rather to the whole period that Christ subjected Himself to the evils of man including the trial,beatings,mocking and of course the crucifiction.He ultimately paid all the wage of sin by His death. The word earth here is used just like the word "world" was in Christ's teaching to signify mans sinful nature.I think it only fitting that the first Adam became the subject of sin in the garden and Christ the Second Adam became subject to sin(mans) in a garden too.So yes Christ died and was entombed but His experience in the "heart of the earth began before that.