I'd actually call MS regularly to check. Twice we've had wait lists miraculously come through at the very time I called. I suspect that if you call they do a manual search and if the days are available you get it. No one seems to really know how the automated system works, but it looks like it does not run continuously. It appears that if you happen to ask for the days before the automated system runs on all the wait lists, you get the days. I'm not 100% sure, but it seems like too much of a coincidence that twice I would have called right as the wait list came through. May be I'm too suspicious (like Michael Banks).