Just saw this article on FluTrackers. This incubation was at least 7 days in her case:
“She had traveled to Wuhan on the 13th to 15th, and traveled to Europe on the 16th to 25th. Coughing symptoms appeared on the 22nd, and the cough worsened on the 25th. She returned to Taiwan by herself, wearing a mask on the plane and filling in the “Health Declaration Card for Passengers Entering the New Coronavirus Pneumonia”, and informed the airport quarantine staff at the time of entry...”
https://www.ettoday.net/news/20200126/1633012.htm
Bet the other passengers were ever so grateful she filled out the health card. Sounds about as effective as a restraining order.