You have to book as far in advance as possible. I believe that is T-330 days with VS. Otherwise somebody else has snapped up the reward seats - this is simply too well known and popular now.

Also note that ANA Mileage Club members get an additional one month head start for booking. So you might NEVER see ANA award flights on Aeroplan, UA, etc. for the dates you want. And of course there is no guarantee that VS will see award space that you might have found elsewhere.

You also need to be willing to position yourself separately to any city in North America that ANA flies to...