Of course, due to T’Chaka’s murder in Captain America: Civil War, T’Challa now finds himself as the king of Wakanda when the Black Panther movie begins.
Normally it’s Wakanda’s king who serves as the Black Panther, but given T’Chaka’s advanced age, it’s not surprising that he passed on the title to his son, the then-prince.
But after years of training, T’Challa began his own heroic duties just seven days before Tony Stark’s debut, though unlike with the Iron Man reveal, presumably only the citizens of Wakanda knew about T’Challa’s newly-bestowed honor.
Although movies like Captain America: The First Avenger and the upcoming Captain Marvel show that there have superheroes on Earth for decades in this universe, Iron Man’s debut is generally considered to be when the MCU’s modern age of heroes came to be (after all, his first movie kicked off this franchise).