A TTD session is typically done the day after a ceremony. This is when I am doing mine and it is also usually an additional item added to your photo package. There are many different types of TTD sessions you can go, from doing shots around town, on the beach, in the ocean, a cenote. It's a prime time for a bride to get beautiful shots in her wedding dress that are relaxed when you don't have to worry about keeping your dress clean because the whole point is that you're going to trash it and probably get some dirt on it!
Here are some great examples for you...
Del Sol Photography Blog