I found this very helpful, and my doctor's latest email:
Flu vs. COVID-19:
The classic flu comes on suddenly - like you were hit by a bag of bricks all of a sudden - high fevers and muscle aches, headaches, congestion - there usually isn’t any question whether or not you have the flu when you have the flu.
COVID-19: more subtle. Often presents as a mild cold - with some runny nose, congestion, sore throat and low grade fevers…but then progresses to increased dry cough and breathing difficulty in some folks around day 8-9 of having symptoms. (This information is based on what my colleagues in CA and WA are currently reporting). 80% of persons infected with COVID-19 have minimal troubles other than a minor disruption in their life.
Because we don't have testing available yet, {if you have symptoms of a mild cold, you} need to act like you have COVID-19 for the greater public health safety and you need to be isolated for 14 days.