Thank you for the clarification and providing more pointers
I'll be planning for Sept.
Preference is more towards avoiding large crowds.
I am an avid runner and do 5-7km runs on weekdays.
I've not done long walks that stretch over 5-6hrs at a time though.
It's something i will start gearing up for in prep for this.
As others have said, listen to your body and stop when your body is telling you to.
Especially in the beginning don't over walk, take it easy and you will develop your own rhythm.
The pilgrims that I saw with the worst blisters and injuries were all either young or (over) confident or both.
From Saint Jean Pied de Port to Pamplona can be a bit busy and so many people like to book a bed for those days.
After Pamplona pilgrims get more spread out and it is less busy and many people like to walk day to day without a fixed plan of where to stop. If this suits your personality then this freedom can be one of the main highlights of your pilgrimage.
If you prefer less crowds then try to stop before or after
Brierley stages but don't have this as a fixed rule, be flexible and adjust to how you feel.
Most importantly, walk at your own pace. Don't be tempted to synchronize with a companion that you meet along the way. By all means agree to meet for breaks or for the day's overnight stop but walk at your pace.
The more that you allow yourself to be open to serendipity the deeper your experience will be.
Enjoy your pilgrimage, Buen Camino