at (someone's) convenience

Translations
в удобное (кому-то) время
Please reply at your earliest convenience.
Пожалуйста, ответьте в удобное для вас время.
Definitions
A phrase indicating that something can be done at a time that is suitable or convenient for someone, rather than at a fixed or predetermined time.
Words
at

preposition
при
someone

pronoun
чей-то
s
чей-то
convenience

noun
удобство