Blu-ray release and pre orders , would they get sold / taken into stores weeks before the release date ?

Right say a new game or film is due for release , you order it online ( pre order ) when would that shop be legally allowed to sell it to you ?
I know sites send it a couple days before hand , you get it day of release sometimes if lucky the post arrives early .
But would you get something that is say released 29th ( officially ) but you get it 15th via the store , would that even happen is that even legal is it different around the world ??