QuickBooks files can be very large - some go back twenty years or more. The Start Date (in the Export Settings window) allows you to retain the data you need from a particular date forward. Please note that choosing a date range is not currently supported.
The start date is where all accounts will have their starting balances set in QuickBooks Desktop. This means that transactions on and after the chosen start date will be converted over. In addition, any unpaid invoice and bill transactions will be retained regardless of when they were recorded.
Although our service currently limits the number of years to 30, we do recommend choosing a maximum of 3 fiscal years for the start date to optimize conversion.