A yearly checkup, with the required shots, is the best way to catch a possible problem before it goes unnoticed for too long.
AN Example:
The first year that I had my Fern she was a SUPER shy cat, so I did not make her do anything that would upset her in any way (while gaining her trust). One year later, at her yearly vet visit, she was only 2 years old then, the vet found some very bad teeth. It was due to her eating only canned food combined with my not looking in her mouth. I NEVER expected to find that on so young a cat. So if I'd have waited to take her in, she would have been worse off.
Gee, I hope that made sense
So in a word, ANNUALLY