I STARTED weaning my girls when they were around 4-5 weeks old by giving them moist canned food for kittens and moistened dry food (mash) for kittens. You can make the mash by adding hot water to dry food and letting it soak, then mashing it up with a fork or spoon. I personally believe it is good to give them both. My reasons for this is that at first, they WILL prefer the canned stuff and from experience, if you start with only canned, they're going to WANT only the canned when they get older. But, if you give them both, they will be more accepting of the dry food as they mature. Giving them a variety of flavours also helps them in not being too finicky.
As they get older, slowly take away the canned and make the moistened dry food more dry. As I stopped wetting the dry food so much, I put in bits of the canned to make it more appetizing. But, eventually they were weaned off the canned mixed with the dry to only dry.
Also, I believe the only thing that REALLY helps in removing tartar and plaque from your cat's teeth is brushing. I would go out and buy some toothpaste and toothbrush for cats and introduce them to having their teeth brushed at a young age.
And moist food is not entirely bad. It's good to give cats some canned food because it contains more moisture than dry, which will help cats that don't drink enough water. (In case you didn't know, if a cat doesn't drink enough water/get enough moisture, they can develop a urinary tract infection [UTI].)
Hope this was helpful.