The rise of al-Mahdi with Divine Authority earlier or later will not affect one who has learned who his Imam is

7. Ali ibn Muhammad has narrated from Sahl ibn Ziyadfrom al-Husayn ibn Sa‘id from Fudala ibn Ayyub from ‘Umar ibn Aban who has said the following. “I heard abu‘Abdallah عليه السلام say, ‘Find out (who the) sign (of Allah, the Imam) is. When you will find out and learn who he is then it will not harm you whether this matter (the rise of al-Mahdi with Divine Authority) will take place earlier or later. Allah, the Most Majestic, the Most gracious, has said, ““On the day when We call every nation with their leaders, Imams. .” (17:71). One who knows who his Imam is he would be just like the one who would present in the tents of al-Mahdi عليه السلام.”