Thanks for your reply! No, actually, we just decided this week that we will be getting married in Mexico, so I really haven't started planning. We're in Toronto, Ontario, but most of our guests will be coming from Montreal, so i would probably need to find a travel agent from there first.
You should be able to find an agent here who is able to book for guests in Montreal as well. Your guests don't have to live here to book with a Toronto based agent Most of the bookings are done electronically as well as the deposit system. I was originally thinking of having my wedding in April of 2016, but we decided to do it a bit earlier.
I'd say that a year is a sufficient amount of time when planning and booking. Do your research now and really think through what you want. Once you find a good agent it will be a lot easier. Once you decide on a resort, your group booking agent will set up a room block for your wedding so all your guests can contact your travel agent and book under your room block. Once you block the rooms, typically you have about 2-3 months for your guest to put a deposit down. Mine is booked with Air Transat and they only require a $50 per person deposit to hold a room/flight.
It will be A LOT easier once you have an agent who is helpful