The answer to this question depends largely on the tradition the witch follows, and the meaning you place on the term "Coming of Age".
In many pagan paths male witches "come of age" or are considered old enough to make their own decisions, when they have reached the age of 12 and have gone through a "Rite of Passage". Some Rites of Passage are as simple as "Tending the Yule Fires" and some require "Dream Quests" or physical tests depending as I said above on the tradition they follow.
In many pagan paths female witches "come of age" when their menses starts. There are usually "Rites of Passage" for the young women as well, all of varying degrees of difficulty.
The other "Coming of Age" for some witches has to do with them coming into their power, which depends on when they start their learning and how dedicated they are to that learning. Many study, not all ever progress to the point where they have true power.
The musical the Witches of Eastwick, opened in London in 2000.
Any age. Even small children could be identified as witches.
Grandma in "The Witches" by Roald Dahl is from Norway.
Witches can be of any age, as long as the individual is old enough to make choices about what they believe and what they want to do. Witches can be female or male and are not different from any other individuals in every community.
Children are included into covens but at what age I'm not sure.
They are born into the world like everyone else is.
Normally, people would not blame the witches. They just said things and Macbeth reacted by doing things. The witches can only be held to blame if you think that Macbeth had no choice in his actions. But if he had no choice, how come the witches do have a choice?
The belief that witches can't step on hallowed ground like several other misconceptions come from the popularisation of fictional witches. Real witches are not restricted in where they can go any more than any other person.
Witches bring the dead back to life as zombies.
Banquo is hopeful that his prophecy will come true because the witches predicted that his descendants will inherit the throne. He believes in the supernatural power of the witches' prophecies and is optimistic about his future and the prosperity of his lineage.
The witches predict that Macbeth will be king and how he will fall. These predictions cause Macbeth to dedicate his life to following the witches predictions, doing whatever it takes to make them come true, or to avoid them.
nio vampier are not in the world only a bat Witches come in covens. Vampires come in clutches.