1/3 lbs per person is plenty, especially if there will be other foods there.
We have a pot luck at the office on Friday this week and my pulled pork has become a required staple. Since it is the day before Memorial Weekend there will probably only be 20-30 folks in the office that day. I have 18 lbs of boneless butt on the smoker today, cooking hot n fast (300F). I will smoke it, rest it, pull it, adjust the flavor profile if needed (I made some changes to my rub this morning because my wife requested adding allspice, cloves, and nutmeg to my standard pork rub), cool it then freeze it. Will take it out of the freezer and put it in the refrigerator 24-36 hours prior to serving. Will put it in a big pot, transport it cold to work, then reheat on the stove (an induction plate actually). There will still be leftovers.
With your schedule my recommendation would be to pull it when it is done. Way easier that trying to pull when cold. Then stick it in the fridge, get it cold, transport it cold to the party in a cooler with jugs of frozen water, then reheat at the party with the stove, crock pot, or oven (slowest).