Hi there! If you're looking to get legally married in Mexico you MUST be there 4 business days prior to the ceremony. Unfortunately that's not a resort requirement, it's a government one! Like the other girls said, if your dates are firm for Mexico, do the legal part at home so you can just show up and have fun without worrying about paperwork, blood tests and all the other stuff!
We're having our symbolic ceremony wedding at the Gran Bahia Principe Coba in the Mayan Riviera.