Is 20 weeks too late for my first ob appointment?

No: The earlier you seek prenatal care the better. If you have put off your first visit though now is the time. It is never too late.

Yes: But that doesn't mean you should not get prenatal care. Being over 20 weeks means you've missed certain critical evaluations (such as early dating ultrasounds, avoiding medications that can cause birth defects, blood tests that look for down's syndrome and spina bifida). But better late than never - get care as soon as possible.