We actually had to do a fair amount of planning in advance even though we want the trip to have lots of flexibility. The first decision was how much time could we both take off to travel and how long do we want to travel. Then we decided on the right month to depart which was approximately one year from when the plan developed. We then plotted the dates and countries of where we planned to visit since we had to book our flights in advance. The rest of the details fell into place as we started making progress on our plans.