Short answer: no.
There's no public schedule, and typically not even a private one. I say typically because there have been cases where a point release is meant to coincidence with a press event. But aside from that, point releases get additional betas when there is additional stuff to test (for example, when a security hole has recently been discovered, and they want to add a patch to it in that very cycle), and they get their final release whenever Apple feels it's sufficiently ready — i.e., when all blocking bugs are fixed.