As salamu alaikum IMAM MAHDI will kmowknow who he is in his late teens.Anyone know anything about spirituality know the HAL comes first its no knowledge its just experince,then the MAQAM comes "its experince and BATIN knowledge"sooner or later in MAHDI case later.MAHDI will not know whonhewho he is from.hadiths he will know from his spiritual state his reality.The first yo make BA'A to mahdi want make ba'a fron reports of hqdiths it will be from the pure noor ALLAH places in their heart.MAHDI will appear in western lands first where he's from he will appear looking like a BLACK ANCIENT ISRAELITE FROM THE HOUSE OF AARON as alantic slave trade,he will be a convert to idlam uneducated,Mahdi will not be lernt in deen islam or even know arabic or even relate to arabs until ALLAH guide him in one night then he will relate to the poor oppress downtrotted,he will be surrounded by DARK SKIN NONARABS they will be his people.He will be over 40yrs when he make his full apperance "with knowledge"his name will not be muhammad ibn abdullah thats arabish? Even IMAM S.MUHAMMAD RAMADAN AL-BOUTI ra said all the name of mahdi are weak!