How can one know that the Day of Resurrection has begun?

The matter of the Day of Judgment is momentous and perilous, involving tremendous events and horrors. "Whoever dies, his Resurrection has come" is a saying narrated as a weak hadith (definition), meaning that a person's death is his minor resurrection. No one will be saved from the horrors of the Greater Resurrection except those who prepared for it with faith and good deeds, as mentioned in the hadith of the man who asked the Prophet, peace and blessings be upon him, about the time of the Hour, and he replied, "What have you prepared for it?" This indicates the importance of preparing for it with good deeds.