になって初はじめて

expression

not until; only when

Expresses that something happened or was realized only after a certain event or condition. Often used with past tense to emphasize the delay or prerequisite.

• 病びょう気きになって初はじめて健けん康こうのありがたさがわかった。

  It was not until I got sick that I appreciated the value of good health.

• 外がい国こくに住すむようになって初はじめて自じ国こくの文ぶん化かの良よさに気きづいた。

  Only after I began living abroad did I realize the good points of my own culture.