About 8 months ago. Last April I think. (Provided I haven't been sucked down into a timewarp and it is even earlier than 8 months ago).

It was only released on DVD if you're hoping for a cinema release.

But fear not! If you can find a black hole, and travel down it, you might, I repeat might (if that theory of black holes is the valid one), end up before the release so you can buy it on release day and then live the next eight months out all over again