What is the normal age for final wisdom tooth eruption?

Variable. It can take a few months to a few years to never. Normal eruption age ranges from about 18-22, female earlier than male. Some are early some are late. If there is room they may come in. If there is not room then they remain impacted. Most need to be removed but not all. See your dentist for a consultation if concerned.
Late teens. Wisdom teeth erupt between 17-25 years of age.