788:
N27908 sked to exit XMN as UA2738 to SFO on 9 JAN local time. This is expected to be the first Polaris/P+ 788. It's not in FlightAware, but the following flight (UA1912 on 8 JAN PST) is shown and the exit flight can be traced back on ua.com.
Note the seat map isn't yet loaded and the seating is still listed as 2-2-2 in J. Hopefully that will update.