Why were people raised right after Jesus's resurrection?
They were raised immediately after Jesus' resurrection to demonstrate the power of resurrection and to fulfill the Old Testament first-fruits pattern. Unlike Lazarus, who was only revived to die again, these were truly resurrected, so it was necessary that resurrection begin with the Creator Himself.
Les teaches that resurrection never took place until Jesus was raised from the dead. Immediately after His resurrection, to show the power of it and to fulfill the first fruits as practiced in the Old Testament economy, people were brought out of graves around Jerusalem, entered the Holy City, and appeared to many. Though Scripture does not say they went up into glory, Les reasons they had to have, because they were resurrected, not merely raised like Lazarus to die again. This fulfilled the whole idea of first fruits.