When is a 63 not a 63?

There was a guy on Ebay with what he said was a 63 Dart,(see link) but it was the same body style as the 62's. I sent him an e-mail to confirm and he said it definately was a 63. My question is, did the new for 1963 style (early A 63-66) come out mid year? Did they make both styles for 63? Is my 63 actually a 63 1/2?

http://cgi.ebay.com/ebaymotors/1963...iewItem&pt=US_Cars_Trucks&hash=item3f01b9470e