I personally would never fly from a new airport on its first full day of operation unless absolutely essential or I had plenty of time to spare - it's impossible to test a new airport so completely that nothing goes wrong. That being said most people buying tickets will not nevessarily know when an airport is opening.
However if the worst that happened was 12 people missing their flight and being given a transfer to a later flight at the airport's expense then it seems like a very small hiccup for a first day of full scale commercial operations