Why did the resurrected saints appear only after Jesus' resurrection instead of before or during His crucifixion?
Christ had to be first, since He is the first to ever be resurrected. Only after His resurrection could other examples follow, fulfilling the firstfruits sheaf analogy. Therefore these Jewish believers came out of the graves after He was raised, were given immortality rather than dying again, and evidently ascended into heaven.
Les explains that the saints did not come out of the grave while He was on the cross; they came out after He had been resurrected Himself, because Christ had to be the first. He is the first to have ever been resurrected. To make the sheaf analogy full, there had to be other examples of resurrection. Some Jewish believers were resurrected from cemeteries around Jerusalem, came into the city, and appeared probably to their friends and relatives. Scripture is silent, but since Christ in His resurrected body ascended into heaven, these saints did as well. They did not come like Lazarus to die again; they were resurrected believers given immortality and no doubt taken up into heaven. This makes the sheaf of the first fruits, the beginning of the first resurrection.