We have had our 3 crested geckos for 3 weeks now, we brought them from Lilly Exotics and we were told they were all feeding on CGD since hatchling, although supplemented with crickets dusted twice a week. They also were given mango puree but we are only giving that once every week or so as it doesn't hold much nutritional value compared to CGD. So at least we knew they were established with the CGD and we didn't need to worry about them not eating it.
We have our 3 in a 30x30x45 exoterra (this is the size they have been in since they hatched in a group of 6, and we are prepared to buy more vivs etc as soon as they hit adolescence depending on their sex and temperament.) with lots of fake plants and hides on the floor and they are fine, are eating and active.
We don't have ours on a heat mat at the moment as the room they are in is always warm and so far hasn't dropped below 70 degrees Fahrenheit, although we may need to in winter. A bulb isn't recommended for geckos from what I have read, as the can get so hot and crested geckos can die in temperatures of 82 degrees Fahrenheit +