Most couples start their planning one year in advance of their wedding date, which is good timing, but over my years of experience, I found that there are aspects of the planning process that is overlooked; your engagement phase.  Many brides jump into planning as soon as the ring is on their finger.  Slow down.  Absorb. Celebrate.  Take the time to enjoy this new transition. 

I suggest you start eighteen to fifteen months prior.  There is nothing wrong with beginning planning one year prior to your wedding date, however, I recommend you give yourselves the time to properly prepare, not just for the budget, also for your marriage. 

Part 1 of the planning is process is to take the first 3 months (18-15 months), to absorb and enjoy your engagement.  Discuss your future with each other and make the necessary announcements.