Night before...

I rub while the egg stabilizes.  Never noticed a difference of doing it the night before 

I am in the day/night before camp.  I doubt the length of time the rub is applied makes much difference but one less thing to address the AM of the cook.  Besides that process reminds me of the enjoyment that will be happening the next day.  Can't put a price on that...

Only do the rub the day before if I'm injecting something into the meat. Otherwise right before lighting/as it's warming up. 

@dougcrann I don't mind at all...

The short answer is that it is something I picked up from reading amazingribs.com and just got in the habit of doing.  Now for the long answer...

From what I remember, Meathead doesn't add salt to his rub (memphis dust).  He prefers to dry brine the meat by adding 1 tsp of salt per lb of meat the night before and then add the salt-free rub before the cook.  I believe his reasoning is the salt helps draw moisture to the surface so benefits from having some time on the meat.  The rub doesn't penetrate the surface so there is no added value in adding the rub too early.

When I started using commercial rubs I continued this habit but added less salt because those rubs already have some salt in them.

Meathead has entire essays dedicated to this, so check out amazingribs.com if you want to hear the reasoning directly from the horses' mouth. 

I hope everyone is enjoying their weekend.  Happy egging all.

I inject the night before and apply the rub the next day while letting the egg stabilize. I usually buy the double pack pork butts snd just inject them through the plastic. Otherwise I'd probably apply the rub the night before as well.