I've had stingy babies go 4 months before taking their first meals. Pink mice are not going to help you. I start my carpets on large hopper mice and they have no problems. Carpets are known for taking large meals. I wouldn't worry just yet. Give him another month and try to reduce movement and handling to a minimum. I'm assuming it's the 75% coastal cross in your sig. Most people will say they are not arboreal, but in my experience they can be very arboreal if given the opportunity. You may offer a perch and present food from beneath the snake if it is perched. Quick movements are what gets their attention. Good luck.