först

In a sentence

• Jag kommer hem först imorgon.

  I will arrive home not until tomorrow.

  In this sentence, "först" is used to indicate 'not until' with a reference to the earliest occasion something happens.

• Först äter vi middag, sedan tittar vi på en film.

  First, we will have dinner, then we will watch a movie.

  Here, "först" means 'first' as in the initial action in a sequence of events.

• Jag måste bli färdig först innan vi kan gå.

  I need to finish first before we can go.

  In this sentence, "först" means 'first' indicating priority or sequence to completing a task.