Praise be to Allah.
The appearance of these three signs, the Mahdi, the Dajjaal and the descent of ‘Isa (peace be upon him), will undoubtedly happen, as is indicated in the saheeh reports. These three signs will appear within a short space of time, as ‘Isa (peace be upon him) will pray behind the Mahdi, and will kill the Dajjaal, as was reported in the saheeh ahaadeeth. As for when this will happen, Allaah knows best about that. As to whether it will happen soon, the texts seem to indicate this, but the question of whether it will be in our lifetime or after is part of the Unseen, which no one knows except Allaah. The Muslim should seek refuge with Allaah from fitan (tribulations) in general, and from the fitnah (tribulation) of the Dajjaal in particular; he should pray to Allaah, openly and in secret, to help him remain steadfast in this world and the next.