I believe that each COTUS serves 1 term divided into 2 sessions. So the end of the first session would be just before Christmas 2017. A “session” is not a “recess”.
Oh, I see, I think.
Congress makes rules, Congress can change rules.
I contend that Obama would not risk his now-tenuous legacy on either an extra-Constitutional SCOTUS appointment or a Hillary pardon. Whatever joy he might receive from a finger in the eye to the Trump supporters, he'll no longer be in position to write the history on either, and can't risk what might yet to be revealed.