When were Surah Al-Falaq and Surah An-Nas revealed, and is the hadith of the eleven knots related to the Prophet's (PBUH) magic authentic?

The two surahs of seeking refuge (Al-Mu'awwidhatayn) were revealed in Medina following the incident of magic, and the Ahadith indicate this. 'Uqbah ibn 'Amir, who narrated the Hadith of their revelation, was with the Prophet, peace and blessings be upon him, in Medina. The Hadith of Zayd ibn Arqam indicates that their revelation was after the Prophet, peace and blessings be upon him, was afflicted by magic. Al-Hafiz Ibn Hajar and others mentioned that the story of the revelation of Al-Mu'awwidhatayn occurred after the incident of magic. As for the number of knots being eleven, no authentic Hadith has been reported concerning this.