Greece is always the first country in the Olympic Opening Ceremony, because the Olympics originated from Greece.
The ancient Olympic Games originated from Greece; also the first edition of the modern Olympic Games was held in Athens - 1896.
Greece always leads the ceremony, the host country is always last. Since the Olympics began in Greece they are given the honor of being the first to walk during the opening ceremonies.
The host nation.
Greece because it is the birthplace of the olympics