The Turkish General Directorate of State Airports Authority has shared an official statement noting that the full operation of the new Istanbul Airport has been pushed back to early March. The airport was officially opened in late October but only a very few flights have been operating from it. At the inauguration the authorities said that all flights would transfer from the existing airport to the new facility at the end of 2018. However, the full transfer date has now been postponed until at least March 3.
The statement, issued to the Turkish press, can be found here (in Turkish): https://www.bbc.com/turkce/46697429