After all nations have entered, the president of the Organizing Committee makes a speech, followed by the IOC president who, at the end of his speech, introduces the representative of the host country who will officially declare the opening of the Games.
The president of the Organizing Committee makes a speech. A speech is followed by the IOC president. This IOC president introduces the representative of the host country. This is at the end of his speech. This representative of the host country will officially declare the opening of the Games. All nations have entered.