YOU SAID:

I think she decided to transition in the early 2000's

INTO JAPANESE

彼女は2000年代初頭に移行することを決めたと思う

BACK INTO ENGLISH

I think she decided to move in the early 2000s

INTO JAPANESE

彼女は2000年代初期に引っ越すことにしたと思う

BACK INTO ENGLISH

I think she decided to move in the early 2000s