drop 1 hour per 2 days, down to 10 per day. Feed well and when you think he has weight on then stop feeding for 1 week. Then fill bottom of the tank with straw that he can burrow under. Then turn lights and heat of completely and put a blanket over the tank. He may take a few days to burrow. Then just leave him be. Have a sniff once every few days to make sure no strange smells. You can then leave him for 2-4 months and he will be fine. It is CRUCIAL that you do not wake him up during this time- just let him sleep.
This works fine as long as temp does not drop below 10 C. You do not want him in a room over 25 C though as his metabolic rate will not allow him to brumate.
I have done this for 20 beardies now and have had no trouble- but this is my experience only, some risk is laways associated with wintering.
When you wake him up, just increase light and heat to normal and remove straw. He will be very alert and eat heaps. 3 weeks later will be ready to breed.