I think it depends on your home and destination airports and how quickly the flights there book up. At my airport, if the fares to MCO come down after the initial release then they don't come down much. We NEVER get DINGs to MCO. I figure I'm best to just book right away and get credits if fares go down. That being said, I have credits that are likely going to go to waste (I'll give them away before just letting them expire but I'm right now doubting I'll use them for my family). Base fares from my airport have gone up since my last trip so I'm not counting on much going forward.