What is the migration date used when the new absence integration is enabled in 25B?

Summary:

In the release notes it indicates the new absence integration will be enabled in 25B, what will be the default migration date used?

Here is the notes from the release notes:

"Starting in release 23B, we introduced an enhanced integration for Absence Management and Time and Labor that included steps for existing customers to migrate from the older to the newer integration. In release 25B, this improved integration will be enabled by default for all existing customers."

When we ran the feature upgrade using a blank migration date - absences only 3 months back were valid, and future absences were invalid. We need to know there won't be any errors if this integration will be defaulted in. When we re-ran the process using the go-live date, it took 2 days for the process to complete in a lower environment - this may cause other processes to pause which would impact system performance.