wollersheim

What can anyone tell me about this. Do we fill it our on the plane? Do we fill it out when we get to our destination? Do we need to fill it out for domestic flights? I see we can fill it out online but only 12 hours before departure but that will be difficult for me to do as I will not have access to a printer 12 hours before departure. We are flying from Calgary to PVR on Dec 7th and then the next morning flying to Guadalajara, which will be a domestic flight. Thank you in advance