Is wrapping a butt in plastic necessary?

If you rub the butt......and place it in the fridge unwrapped you will find it sitting in a puddle of it own juices.  Wrapping it keeps those juices next to the meat.  Some of the rub does come off which is why most will re-apply rub prior to going into the smoker.  Also there is no need to use mustard (doesn't add flavor) because the rub will draw moisture out and will help the rub stick. 

I rub and place in fried overnight.....always have but you can do what fits your timeline.  Remember you are "marinating" the Butt when you let it sit with rub.

Take the cold butt out and put it in the smoker.  A cold piece of meat takes smoke better than a room temp one.   So NO don't let it sit.  Pull from fridge.......re-rub......put in smoker.

Scott

Give us your plan.......how many pounds is the Butt?  What kind of smoker?  The more info you give us the more we can help you and answer your questions.  We want to make sure you have a successful first smoke. 

Oh and Pictures......because........

I have always rubbed my butts right before I throw them on the smoker. There are no wrong or right ways to any of this. Just do what feels natural. The only thing you have to remember is relax and enjoy the ride. Don't panic if you have any concerns the are plenty of well informed people on here to help you along.