As far as Islamic fiqh is concerned, young boys are allowed to lead adults in Prayer. Imam Ash-Shafi`i says that young boys can lead adults in optional and obligatory Prayers. Though other schools of fiqh allow the young boy to lead adults in optional Prayers only, we accept the opinion of Imam Ash-Shafi`i in some situations so as to teach young boys how to pray.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto,Ontario, Canada, states the following: If a young male has attained the age of tamyiz (discernment) and are well versed in the rules of Prayer, besides being fully conscious of the rules of taharah (ritual purification), then they are eligible to lead Prayers in your own home. However, parents should not teach them to look forward to leading Prayers, for we are not allowed to look forward to the same. The Prophet (peace and blessings be upon him) said, among those whose Prayers will not be lifted to Allah is “a person who leads people in Prayer, while they dislike him.” According to Imam Khattabi, a great faqih and scholar of Hadith, the above hadith is intended to target those who impose themselves as imams without being eligible to lead.
It is important to know that the rules of imamah have been clearly stated in the sources: “The one who is knowledgeable in the Book of Allah should lead; if they are equally proficient in the Book of Allah, then the one who is most conversant with the Sunnah should lead; if they are equal in this, then the one who made hijrah first should lead, if they are all equal, then the one who is most senior among them should lead!”
Having said this, however, I must point out that there is nothing wrong in occasionally asking a young kid to lead in order to give them the necessary training and confidence, if they fulfil the conditions I have mentioned earlier.