Lee,
As Jack and John stated it will be sometime in 2013 if reservations are sufficient.
Typical Sunset experience with B&O power is that most reservations come in within the first few months so production can be started earlier than with some other projects.
I intend to display my 2 rail Westside modernized P-7 at York in October which will also help build reservations. Although my model has the shorter tender as used in the P-7c subclass I may paint my T-3 tender blue to show what a P-7e looks like.
One difference will be that the P-7e will use the tender with rounded water cistern top whereas the T-3 used the squared water cistern.