Multi-class talents

Am I reading it right that I can only take a multi-class move once?

Example (doing it wrong)... Barbarian levels to 2nd level and takes the fighter's signature weapon. Barbarian levels to 3rd, and takes the fighter's heirloom move

Example (doing it right)... Barbarian levels to 2nd level and takes the fighter's signature weapon. The barbarian has to wait until 6th level to take the fighter's heirloom move correct?