If this property is set TRUE (checked), the Web Part will initiate (fire) its connection when the page containing the part ...

If this property is set TRUE (checked), the Web Part will initiate (fire) its connection when the page containing the part is first loaded in the web browser. The Data View sends the data for the first row in the result set XML data to the Web Part that is the consumer of the connection. This property allows a Web Part page with connected Data Views to have a reasonable initial state when the page is opened in the web browser.