You book it bit by bit, as award availability opens up. Once you see availability, book it, or risk losing it. Then add other flights, later.... do you book one of these awards when there isn’t availability for all the sectors? ...
Award seats don't usually hang around forever.
Edit: It requires a few calls to the Call Centre @ 5,00 points/passenger/phone call. However, this is still a very good deal, so long as you have a few points up your sleeve.
