How should data migration be managed to keep the original created date from a legacy system?

Managing data migration to retain the original created date from a legacy system involves ensuring that the migrated records reflect the same timestamps as they had in the old system. When "Set Audit Fields" is enabled during data loading, Salesforce allows for the preservation of standard audit fields, including the CreatedDate. This option is particularly useful as it avoids the complications of needing to manually update records after migration or creating additional fields.

Using this feature minimizes the risk of data integrity issues, as it directly instructs Salesforce to assign the original creation dates to the respective records upon import. It streamlines the process and ensures that the historical context of the data is maintained without further manual intervention, making it a clear and effective approach to data migration in this scenario.

Other options involve more manual or complex processes, which could introduce errors or require additional maintenance. For instance, updating records post-migration may lead to inconsistencies or loss of historical accuracy if not done meticulously. Similarly, creating new fields adds unnecessary complexity and might not address the requirement of keeping the original created date. Writing an Apex trigger, while feasible, adds development overhead and can complicate the data loading process. Therefore, enabling "Set Audit Fields" stands out as the most efficient and reliable method.