"Use First" is a restaurant industry term used to refer to the accounting concept of FIFO - first in, first out. It can be used as both a noun and a verb. As a cook, your use first of a component such is aïoli is the one with the oldest date. That is the product you will utilize during service first. Note however that just because a product is the oldest it should be used during service. As a general rule, any component should be kept for a maximum of three days before it is too old and discarded.