Dr. Lecter was imprisoned a long time before being moved to the glass cell. Wouldn't he take advantage of any slip up by the guards that presented itself at any time? His exploited his new jailers' inexperience, but I don't think he had a plan before he actually saw his new prison.
I'd like to know the first time somebody started singing that damn "mama's going to buy you a mockingbird" song right before something awful happens. It's been done to death in a lot of horror flicks.