like Rachel said, Sunday weddings at LC used to be rare/unheard of. i think most people want their wedding on Sat or Friday. but since you're in Mexico on vacation, it's not as important! i know ALL Sundays can't be booked up, but are you trying to get married before a certain time or something?
also, like Rachel said, i think most (all?) brides go over early - you really won't have time to get ready otherwise. but if that's not important, then i suppose you could go over in the afternoon/evening with everyone else.