Signs of the Last Day are discussed under lesser and greater signs. The loss of knowledge and the spread of ignorance and turmoil are examples of lesser signs.
Major signs include the Mahdī, Dajjāl, the descent of Jesus, Gog and Magog, the sun rising from the west, the Beast of the Earth, smoke, the destruction of the Kaʿbah, and the final fire.
These reports are not an invitation to invent fixed dates. The purpose is to affirm reliable reports and prepare through faith and action. Unsupported certainty about details or sequence should be avoided.