Muhammad and Aisha
The majority of traditional hadith sources state that Aisha was married to Muhammad at the age of six or seven, but she stayed in her parents' home until the age of nine, or ten... Muhammad, then 53...
that the Prophet (*) married her when she was six years old and he consummated his marriage when she was nine years old. Hisham said: I have been informed that `Aisha remained with the Prophet (ﷺ) for nine years (i.e. till his death).
Narrated Aishah: The Messenger of Allah married me when I was seven years old. The narrator Sulaiman said: or Six years. He had intercourse with me when I was nine years old.
The Prophet... married Aishah, may Allaah be pleased with her, when he was fifty-three years old and she was a girl of nine years old. So being older does not harm. ... the age should not be an excuse and it should not be considered something shameful, as long as the man is righteous and the woman is righteous. May Allaah reform the situation of us all. (Fatawa Islamiyah Volume 5, The Book of Marriage, page 169-170)
Iddah (the waiting period)
Iddah is the period a woman must observe after the death of her spouse or after a divorce, during which she may not marry another man. Its purpose is to ensure that the male parent of any offspring produced after the cessation of a nikah (marriage) would be known.
And those who no longer expect menstruation among your women - if you doubt, then their period is three months, and [also for] those who have not menstruated. ...
They may not have menstruated as yet either because of young age, or delayed menstrual discharge as it happens in the case of some women, or because of no discharge at all throughout life which, though rare, may also be the case. In any case, the waiting-period of such a woman is the same as of the woman, who has stopped menstruation, that is three months from the time divorce was pronounced. Here, one should bear in mind the fact that according to the explanations given in the Qur'an the question of the waiting period arises in respect of the women with whom marriage may have been consummated, for there is no waiting-period in case divorce is pronounced before the consummation of marriage. (Al-Ahzab: 49). Therefore, making mention of the waiting-period for the girls who have not yet menstruated, clearly proves that it is not only permissible to give away the girl in marriage at this age but it is also permissible for the husband to consummate marriage with her.
Jean-Léon Gérôme - The Snake Charmer
On average, girls begin puberty at ages 10-11; boys at ages 11-12. Girls usually complete puberty by ages 15-17, while boys usually complete puberty by ages 16-17. The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12-13; for males, it is the first ejaculation, which occurs on average at age 13. In the 21st century, the average age at which children, especially girls, reach puberty is lower compared to the 19th century, when it was 15 for girls and 16 for boys.