Let me re-tell what I mean Kingdom Heart Zero:

Lets look at what order Capcom made for Resident Evil;
1) Resident Evil
2) Resident Evil 2
3) Resident Evil 3
4) Resident Evil X Code: Veronica
5) Resident Evil 0
6) Resident Evil 4
7) Resident Evil 5

If the story of the 'next' Kingdom Heart happen before KH1, then it would be fair to called it 'Kingdom Heart Zero'.