I feed at night usually, between 10 to 1am. I believe they are actually crepuscular versus nocturnal, so I'd venture to say that the most 'natural' times to feed are at dusk and dawn.
The one thing I noticed had a huge effect on their eating habits was bumping up the temps even 1 degree on average. I went from 88 hotspot to 90 hotspot and they were all hanging out of their hides looking insane and feeding them felt like playing a game of hungry hungry hippos.