What day is it?
The 23rd.
We're getting there, aren't we?

To death, was the first thing I thought.

Where else could she mean? September? The end of summer? To cold weather probably.
The earth ship, it moves towards seasons. Rotating and spinning make less sense

And then what when we get there? What changes?

In fall everything changes. But that's probably not what she meant.
Well,
we're getting there. Wherever she's going and wherever I'm going, we're getting there.