I started early when he was a few months old and he does not hate it.
But i need to do it more.
My 17 yo had so many dental problems and no longer can have extractions but we are pretty sure he is not in pain with whatever he has left. He has a dental fistula that healed.
I’ve never brushed a cat’s teeth, but I’ve admittedly never had a cat it’s whole life. My sister has a 21 year old cat, and she doesn’t brush her teeth. No dental problems, either. Her late kitty had dental issues before he was 10, though, and he had to have a lot of teeth pulled.
I had a cat put under sedation to have his teeth cleaned and they warned me he might die. I don’t think a cat would let his teeth be cleaned awake. If you can do it it doesn’t need to done but a few times a lifetime is my guess. A dog has his bones to naw on.