There's an advert on the back of the latest issue of the Greenwich Time "newspaper" from the Council for the Vue cinema, it says that it opens on the 29th of June.
I was there last night and it looks pretty open already, people were buying pop corn and heading on in. Vue's web site also seems to be giving film times.
So if you fancy a pop down there before it's official opening at the weekend then go for it.
However a word of caution... Last night was "special" as there was a gig on, if you do plan on going I'd call (08712 240 240) before doing so.