I've been watching the fares since they first became available in March.
One Saturday morning in Early April (?), I lost all my spreadsheets with the prices I had just found the night before. When I checked Delta again, I found that the price had dropped $62 per seat overnight. Needless to say, we jumped in the car and drove out to the airport to get our three tickets for January and one for me for this August.
When I checked for my borther on Monday the prices had gone back up. When I checked the next weekend, they were down again and then back up on the following Monday. They haven't been anywhere near that low since!
For me, they were lower than I ever expected they would be from my choice airport. Also, when I got my tickets, I asked the agent if the price went down, could I get a refund. She said I could get a voucher good towards future flights. I didn't go into details, but it hasn't mattered because the flights haven't and probably won't go that low again.
In my experience - keep checking - often, but that's just my opinion.
Jen H.
Maine, USA
86 days to WDW!