When Fotos are released, Summit hardly notifies anyone. LOL However, we do have one official (well, two if Du count Bella's hand with feathers) Foto that was revealed in EW last month.
This is the only Foto (minus the picture from Bill Condon's twitter) that has been released from the movie. Other Fotos are probably manips.
Again, when they release photos, they hardly ever announce that they are releasing Fotos unless it's for promotion. If Du are talking about the teaser posters, they probably will announce it. Summit loves to make a huge fiasco about posters oder trailers haha It'd actually be kind of cool if they had a mini trailer for the superbowl oder something :P
But anyways, we won't see any Fotos of Breaking Dawn unless 1) Summit tells us (which is rare), 2) they're leaked (which is not impossible), oder 3) for promotional reasons. However, I'm sure they will release some soon. They still have about 3 months til BD wrap, but I know they know Fans are itching for something.
However, I'm sure Von summer, we'll have a teaser trailer. I'm thinking May. Possibly April. Rob's Water for Elephants movie is in theatres in April. I wouldn't be surprised if Summit tried to promote BD then.
Sorry, off topic. Answer to your question. No, we do not know when official Breaking Dawn Fotos will be released. We only know of one (possibly two if Du count the Twitpic) official Fotos and that's from EW. :) Hope this helped!