Activity for N2scrapn

I have my guest list at appox 175. I will be buying my linens as it will be cheaper than renting. My question is, how do I know how many to purchase/plan for without waiting till last minute when the RSVP's come in?

I am planning a fall wedding in a barn! My colors are all fall colors browns, oranges, yellows etc. My BM dresses are brown and my dress is Ivory. I am planning on using pumpkins as centerpieces. My question is, would it be too many colors to use...