Priest: The Title Appears After the Institution of the office
Source: Nav
Leviticus 21:10–15
The priest who is highest among his brothers, who has had the anointing oil poured on his head and has been ordained to wear the priestly garments, must not let his hair hang loose or tear his garments. / He must not go near any dead body; he must not defile himself, even for his father or mother. / He must not leave or desecrate the sanctuary of his God, for the consecration of the anointing oil of his God is on him. I am the LORD.
Numbers 3:32
The chief of the leaders of the Levites was Eleazar son of Aaron the priest; he oversaw those responsible for the duties of the sanctuary.