UPDATE: Nelson was apparently being sarcastic. No trailer on July 12th.
Nelson, admin of Michael Bay's official forum has possibly just dropped some huge information on us today. When asked about a trailer for Transformers 4, he actually answered: "Next week Friday". A forum member suggested he was joking, but I pointed out that he would not joke around with something like that since it could be plastered around the internet very quickly, which could get him in trouble. So, in my opinion, this is true, and we should be getting a small, quick teaser trailer on July 12th.