Exodus 19 · a question people ask
Who are "the priests" in 19:22, before Aaron was made a priest?
The chapter doesn't say. It speaks of "the priests also, who come near to the LORD" (19:22), and the LORD tells Moses, "don’t let the priests and the people break through" (19:24). Aaron and his sons are called "that he may minister to me in the priest’s office" later (28:1). A few chapters on, Moses "sent young men of the children of Israel, who offered burnt offerings" (24:5). The text doesn't say whether those are the same men.
The verses
“Let the priests also, who come near to the LORD, sanctify themselves, lest the LORD break out on them.””
“The LORD said to him, “Go down! You shall bring Aaron up with you, but don’t let the priests and the people break through to come up to the LORD, lest he break out against them.””
“He sent young men of the children of Israel, who offered burnt offerings and sacrificed peace offerings of cattle to the LORD.”
““Bring Aaron your brother, and his sons with him, near to you from among the children of Israel, that he may minister to me in the priest’s office: Aaron, with Nadab, Abihu, Eleazar, and Ithamar, Aaron’s sons.”