I asked this question when I completed my Stage 2 (I obviously wasn't confident! Ha)
If you fail at any point BEFORE Stage 3, you have to wait one year from the date of your Stage 1 tests.
If you fail at Stage 3, you have to wait one year from the date of your Stage 3 tests before you can start at the beginning again.
Basically, the point is, if you fail Stage 3 it's because they didn't like your team work skills or they didn't like you in the individual interview, which isn't going to change if you wait a few weeks... lol