Is it too soon to start the countdown to January 20, 2020?

Of course, if we're lucky the current President may have left the office before January 2020, either voluntarily or by force (impeachment).
I had a secret hope that the inaugural speech would contain an announcement of resignation, but that was too optimistic.

Pence would be no prize, but at least he is closer to normal psychologically. I suspect Pence will be very much involved in formulating policy anyway, though he seems in many ways to be a syncophant.