To me it makes more sense if the Dean scene at the end of The Winchester pilot was not set in Heaven.
They could’ve out the old plates back on after Chuck was gone.
Also in this scene the cooler is in the back seat and the amulet hangs on the rearview mirror – both not the case in Dean’s ride around Heaven’s back roads in the finals as far as I recall!
The feeling I got from the heaven scenes w as that only a few hours passed for Dean until Sam joined him. It never even got dark. Not enough time for some detective work on his origins.
I DO really appreciate, however, that the Dean scenes at the end of TW pilot had the SPN blueish-cool look and feeling to them!!