his/her first steps
Je n'étais pas à la maison quand le bébé a fait ses premiers pas.
I wasn't home when the baby took their first steps.
Le bébé a fait ses premiers pas ce matin.
The baby took its first steps this morning.
Notre Paula fait ses premiers pas, Alex !
Our Paula is taking her first steps, Alex!
— Good Bye Lenin! (2003)
J'étais là pour ses premiers pas, ses premières dents, ses premiers mots !
I was there for his first steps, his first teeth, his first words!
— Demain tout commence (2016)
Son père guide ses premiers pas vers la musique.
Her father guides her first steps into music.
— The Tall Blond Man with One Black Shoe (1972)