Like said before, get it all in writing. When you get the head count of people eating, figure out how much food you'll need and then add some more to cover last minute add-ons, overeaters, mistakes, dropped food, etc. Are they expecting you to serve, too? Side dishes? Or...just meat.
Once you get the facts, make a plan, including a time table and stick to it. Many here will help you get through it.
Blessings on your preparations and future cook.
Large BGE x 2, Small BGE, Big Steel Keg, WSM, 22" Weber Kettle, Charmglow Gasser, The Holy Smoked UDS and her sister UDS, and one custom trailer-ed smoker. The universe's fastest and most accurate Thermapen. (Replaced by Brethren)
IMBAS Certified MOINK Ball maker
Thanks, Grillman, for the avatar!
And now, brethren, I commend you to God, and to the word of his grace, which is able to build you up, and to give you an inheritance among all them which are sanctified. [Acts 20:32 KJV]