アイダホの時間は日本の時間から１６時間前もってあります


Is this sentence explaining time difference structured correctly?

> アイダホの時間は日本の時間から１６時間前もってあります。

It's supposed to say that the time in Idaho is 16 hours before the time in
Japan. If it's incorrect, try to help me figure it out without telling me
exactly how to say it.




I'm afraid to say it's incorrect. 前もって means _beforehand_ or _in advance_.
This is used when someone does something in preparation for something.

Try using 進んでいる or 遅れている instead.

