Hi,
Last year, I was an awardee from the competition's short list of alternates. I got the first notification that I had been put into the waitlist at the end March. My committee was 'Computing Sciences' and I was ranked 62 out of 133 applicants (in top 46.66%) in my group.
I got the good news on the 2nd week of July that the funding had become available and they are going to give me the award.
Funding may become available from two sources:
1) Some CGS-D awardees goes to foreign universities and the award comes down to PGS-D,
2) Some CGS/PGS-D awardees declines the award, because they have better scholarships (such as, Vanair)
I heard that some applicants got the award notification (from the short list of alternates) as late as October for a given year. So, I would say, don't hold your breath too tight , if you are in the waitlist.
Relax, and wait for the magical moment of euphoria, which I had in last July. :)