Maybe the 1000 stardate units per earth year are just a coincidence and it doesn't match exactly.
I am curious what the reference frame for the system could be.
A day is one rotation around it's own axis of a Planet. Different planets, different day lenghts.
One month equals One moon cycle. Some planets don't have a moon or several, they might have different Systems entirely.
One year is lap around the Sun, etc...
So the logical reference for all spacefaring races in the neighborhood would be rotation of the galaxy?
So if 1000 units happen to be roughly one earth year, what part of a galactic "day" would that be?