It will really depend on your cat, how often she will need a clean. Has your vet told you she needs a teeth cleaning? One of my cats is 4 now, and he had his first teeth clean a few months ago. I hadn't brushed his teeth for the first 2 years. You kitty will likely not need a teeth clean for a few more years.
My oldest cat, who is about 9, however, needs his teeth cleaned at least once a year. I brush his teeth every day. He just has really bad genes. I don't know of anyone who does dental work on a cat more than once a year, unless they are a bit older (ie: at least 5 years).