French phrase
Veuillez me prévenir avant de ~.
Meaning
Please let me know before you ___.
When to use it
A polite request for advance notice before someone comes. It is formal and can sound stiff among friends.
Example dialogue
Veuillez me prévenir avant de venir.
Please let me know before you come.
D'accord, je vous préviendrai avant de venir.
All right, I will let you know before I come.