How long does it take for cefdinir to start helping bronchitis? We're on day three and not seeing improvement.

Likely viral. Most of the time people go to a doctor for coughing, congestion and drainage and request help with treatment. Typically these condtions are viral or allergic related and antibiotics will not do anything to help "clear" them any faster than regular rest and otc drugs will. If you are having significant wheezing you need to consider breathing treatments and return to your doctor for further eval.