You can customize date checking in Preferences.
Date Preferences are accessed via the File menu | Preferences | Date Limits tab. You can have the Preferences set to check dates only when adding new records or when both adding new records or editing existing records. Or turn it off.
If you seldom enter old hours or dates, you can choose temporarily "Don't check any dates" in Preferences. Save and exit Preferences. After you are done adding old data, go back into Preferences and set it back to check dates.
These settings enable you to set limitations on date entry fields in order to prevent data entry mistakes with dates being too far in the past or the future. You can set limitations on any or all date fields by simply checking the options and filling in the limiting length of time. For example, you can choose to allow hours to be entered up to three months [90 days] ago or farther back when you are entering old records.
It's probably best to uncheck date fields which involve years instead of months, like Drivers License Renewal and MoU dates.
Alternatively, you can turn off date checking temporarily. Choose "Don't check any dates" in Preferences | Date Limits. Save and exit Preferences. After you are done adding old hours, go back into Preferences and set it back to check dates.