A full return to service date is pure speculation. I'm convinced the FAA (after due diligence) will return the Max to the skies and the US airlines will gladly launch them. But there are other elephants in the room. Arte other certification systems going to accept the FAA's recertification at face value? You can bet in the current climate that China won't. Ethiopia and Indonesia are going to be very sceptical as well. And what about the training? If pilots require practical training to convert to the Max, there aren't many Max simulators available right now. And you are going to have to convince the public the aircraft is safe. The IAG order was a big vote of confidence, but I'm sure we are going to see more order cancellations.
https://www.bbc.com/news/business-48899588