I try to book award travel 331 days in advance, when the flight first appears in Delta's reservation system. Even that doesn't always work! I have two M-class tickets to France in June/July. Upgrades cleared immediately on the outbound flight, but even with Platinum priority, we have been on the waitlist continuously since August for the return flight (from Nice). Interestingly, this flight is actually selling out -- not too many seats are left on the seat map. Two of my kids may end up flying coach!

Bruce