From what I see in Pub 527, the IRS defines when an asset is considered placed in service.
You place property in service in a rental activity
when it is ready and available for a specific use
in that activity. Even if you aren’t using the prop-
erty, it is in service when it is ready and availa-
ble for its specific use.
As I see it, the key words are "ready" and "available".
