You've still got a youngster who you haven't had for very long, so part of what he's doing is getting used to his environment. I am a bit concerned about you feeding him at night. For me, I feed in the morning, and never less than 4 hours before lights off. Sure sometimes my guy will eat later, and it's not the end of the world, but you want your cham to get in the habit of eating and then digesting his food during the day. Also, your cage is a good size for him now, but start planning for about 3 months in the future when you will need to upgrade him to a larger size.
I digress, your question was about lighting. I mimic the outside light, as I have a window in my cham room. I typically stay to a 12 hour light schedule, but in the summer when the days are longer I'll switch to 13 hours. When lights go off it's all at once. Some members on here have a moon light that they run for an hour to transition their chameleon from daylight to dusk, and then they shut everything off at night. It's your preference, really. Good luck with your new little one!
