The coronation has not been held
http://www.nationmultimedia.com/deta...ional/30335737
It is likely to be held in the Royal Palace, by Brahrams when the palace advises.
King Vajiralongkorn’s formal coronation is expected to take place later this year following a year of mourning and the late king’s funeral.
https://www.reuters.com/article/us-t...-idUSKBN1EX0PT

Maybe Frequent who sits by the newscasts rigidly waiting for something to happen ,could find out.