Hannibal is the audience. Here is the sequence of events: Tobias meets Lecter at the benefit when Franklin introduces him. Tobias follows Lecter planning on killing him, but discovers Lecter dismembering a body in a bus. Tobias then stages a very elaborate crime scene that will get lots of public attention. He makes remarks to Franklin that he knows Franklin will carry on to Lecter (Franklin even realizes that Tobias likely intended for him to do so). The result, as desired, is that Lecter deduces Tobias is the murderer and makes contact.
The amount of time in between is not that important. A painter's intended audience might see the painting well after it's completed.