Variety reported a few days ago that there was theoretically going to be some delay for tent pole movies, including Justice League. But according to WB sources, tracked down by IESB, this is simply not true.
According to the most recent IESB article on the JL movie, WB says that the cast is 100% locked, but sworn to secrecy. In addition, the WB insiders say that the cast will be announced this week. So we can only thank the gods of movie making for that.