Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Volume 11, Page 23, Fatwa No.10938
Question: I performed Hajj when I was ten years old and, once again, when I was thirteen years old. So, do both of these Hajj’s constitute the obligatory Hajj?
Response: The Hajjs’ as mentioned suffice the obligatory Hajj if they were [performed] after you became of age, either by the excreting of semen through a wet dream, or the appearance of pubic hair around the pubic region. This is because the male and female become of age by either of these two occurrences. Also, reaching the age of fifteen years and beginning the menstrual cycle in the case of women.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad (sal-Allaahu ‘alayhi wa sallam) and his family and his companions.