ANSWER - I think it very much depends on both your own natural understanding of your child and what you mean by witchcraft.
Children mature at different rates and what is right for one child isn't for another. I know one witch who regularly involves her similarly aged child in seance work and another who won't let her son join the family coven until he reaches 18. Two very different approaches but we can only assume they are appropriate for the individual children.
I don't see any reason why a young child can't be introduced to the craft. It is easy enough to incorporate some child friendly activities in what we do. I'd have been delighted as a six year old in getting involved in mixing herb concoctions, learning about wildflowers, discovering how to channel energy and being taught how to draw protective magic symbols. It's also never too young to learn how to invoke protective shields or how to use meditation to maintain a healthy frame of mind. All these can be made fun and interesting to a child. There are elements I would personally stay away from with a six year old, I wouldn't start talking about spirits or hexing, nor would I introduce them to complicated casting methods. I'd suggest you keep things lighthearted and be guided by how the child reacts.
The comment in your question that did cause a raised eyebrow or two was that you want your child to learn about witchcraft and your tradition. No mention as to what the child wants? I'd be comfortable exploring magic with an interested child - I would be far less comfortable imposing adult ideas and traditions onto a child who shows no natural curiosity. Beware of imposing your own desires only to find you push too hard and your child rejects what you want to teach them. I'm afraid I also have to warn you that your child - even if inclined to the craft - may show no interest in your own specific tradition. Introduce by all means but resist pushing. As any rebel knows there is no quicker way to push your child away from the path you want them to follow than trying to force them onto it.
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