Stuffing meat cannelloni and refrigerating to be cooked the next day
Is the meat cooked or not ? it's not clear.

I would prepare the stuffing, cook it all and cool it down and stuff the cannelloni and put that in the fridge.

Personally, I would bake it all, sauce included the day before and cool it down and put that in the fridge. (I treat that the same as a lasagna).