You will have a great Camino! Take a breath, understand that if you are going on a pilgrimage then things will work out. An old lesson that I learned long ago is that being in control is an illusion.
First, spend some time looking at the forum. You will find a wealth of information and the vast majority of it will be helpful to you as you being to plan.
Second, decide how much time you can devote to the Camino. Are you going to walk the whole thing, the last 100 km (both of which will earn the compostela, anything else will not). If you are going to walk the whole Camino, pilgrims often average 26 km/day, which would mean that a
Camino Frances takes about 30 days to complete. Many other pilgrims go slower, take days off, etc. and thus take more days...say 33 - 36 days. In addition, some will spend a few days in Finisterre or stay in Santiago de Compostela touring the coast/city and relaxing/reflecting on the Camino. Decide how much time you are going to allow yourself to walk and then those are your dates. IF you run slow then you can always speed up your Camino by taking a bus for a short portion to catch up to your schedule. Does that make sense?
Third, you have a lot of time to prepare. Many prepare physically, particularly those who lead a more sedentary lifestyle; others prepare spiritually/emotionally, etc. Take some time to read some books about pilgrimage, or the history of Santiago de Compostela; the more you know about history, culture, etc. the more enjoyable the Camino.
After you have spent some time reading, please continue to ask questions. Forum members enjoy helping those who are seeking to begin their Way. In many ways, we begin our fist steps of the Camino when we respond to that still small voice by saying, "Yes, I will go".
Buen Camino,
Michael