Yup, you just wait for the fare to come out. I believe in order to get the DING rate both ways the dates of the DING have to both be within the timeframe. For example, if the offer is for travel to/from Orlando from Dec 4 - Dec 19, your travel dates must both fall between them.
I am no expert at it at all, but it was a lifesaver for our next trip. Some of us are driving, some flying, and we were able to get 3 tickets that normally would have gone for $630 combined ended up costing us about $440. So we got exactly the flights we wanted anyway and saved almost $200.
If you post where you are flying out of perhaps others who have gotten fares out of that airport can give you some more specific advice. That's what I did when I first downloaded DING, and it helped to hear others had been successful with my location as I was patiently waiting. I only had to wait a few days, though - I was pretty lucky.
Good luck yourself!
MP