I'd wait a few months
My husband just visited the dentist and while there asked about me. My dentist (who's great: no mercury, "holistic") advised that I wait a few months to come in for a cleaning. I think the logic was that at this point in our pregnancies, you really don't want to potentially introduce any kind of infection and that in a few months, baby/pregnancy would be more resilient.
Our dentist also said that when I do come in, to make sure I tell the hygienist that we're expecting so she just do a "gentle cleaning" and go easy on my gums.
Good luck! I'm overdue for a cleaning and can't wait!