Whatever time you need, it better be fewer than three months.

With a Warren or Booker pick for VP, that would have allowed the Republican governors of those states to appoint their interim replacements, which would have given Republicans even more incumbent status in the Senate heading into the next elections.  Control of the Senate, if you haven't noticed, is also extremely important for a progressive agenda.  Kaine's replacement will get picked by a Democrat governor, and he happens to be both popular in a swing state and has a decent broad, folksy appeal.  He wouldn't be my first choice, but it was a generally decent strategic pick and his actual record is pretty good on progressive values.

The DWS thing is admittedly very stupid.  I don't have anything good to say about that one.  But it's still a small thing in the big picture.