I just double checked and the link to the VRBO site worked fine, the calendar seemed to be working on the site, and I was able to get to the email link but didn't try to send the email.
I think renters figure that they have more time this year to rent places because there are more places available to rent. I think the people who have specific desires (location, cost, number of bedrooms, etc.) are better off booking early because even though they're likely to find something to rent, but it may not have been the ideal option for them. (but then again, I'm the kind of person who books vacations about a year in advance -- but I do get nice places and save some money by doing so). I found a fantastic place in Waikiki by booking early last year and a great place in Italy for this summer by booking in November this year -- both through VRBO. It would have been harder to find a place that meets all our preferences (number of bedrooms, location, cost, style) if we had waited.