first come, first served

first come, first served  {truncated sent.},  {informal}

If you arrive first, you will be served first; people will be waited on in the order they come; the person who comes first will have his turn first.

Get in line for your ice cream, boys. First come, first served.

The rule in the restaurant is first come, first served.

The team's owners announced that tickets for the World Series would be sold on a first come, first served basis only.

There are only a few seats left so it's first come, first served.

Compare: EARLY BIRD CATCHES THE WORM.