How much charcoal should I use tomorrow?

I changing too many things for my cook tomorrow and could use a suggestion for how much charcoal to put in my basket and how much to light. I'm planning on getting up at 5:30am tomorrow and lighting my UDS with a terra cotta diffuser for a 7lb pork butt. I'm targeting cooking in the 250* - 275*. It's supposed to be around 25* outside. I got 1/3 a bag of Kingsford and several 10lb bags of Royal Oak BRICKETTES. This will be my first long cook with a diffuser, first cook with RO brickettes, and first long cook in this cold of weather. I really don't want to run out of fire 2/3 of the way through.

Thanks,

Thanks all for the suggestions. I'm not sure how big your baskets are though... I made mine 13.5" dia and 12" tall. I think most are more like 8" tall. My metal was 12" tall so that is what I went with.

I've been typically loading in 2/3 of a bag of kingsford and have enough for 10 hours. I think I'll go ahead and use all of the 10lbs of royal oak and the 3 lbs of kingsford. It should be more than enough.

I do snuff it out. But often my charcoal gets a little moisture prior to my next use and isn't good. Not always, but enough that I don't want to just load in too much. Especially now that it is winter and charcoal isn't onsale every week.