When does the dealer know the VIN?

My dealer has told me that it is a May build and should probably be here early to mid June. I asked for the VIN and he said he didn't have it yet. I have read some conflicting answers on pc. Do they get it when it ships from Japan. When it hits port? When it gets off the train (been told in Chicago for me).

I emailed him Monday for an update and he said "heard about someone elses prius but yours hasn't hit the list yet." Does anyone know what list he is talking about? sorry for all the questions but it is hard to get answers from my dealer.