к тому времени как ему исполнилось

к тому времени как ему исполнилось 17, у него уже были две профессии и он поменял несколько мест работы

Результаты (английский) 1:

by the time he turned 17, he already had two professions and he changed a few of the places of work

Результаты (английский) 2:

by the time he was 17, he already had two professions and he changed several jobs

Результаты (английский) 3:

By the time he was 17, he had already had two professions and he changed a few places of work