Hi, I have been in the same position as you and also due to work walked three separate "legs" of the Camino before I finished work and had the time to walk the full route.
I would recommend starting in St. Jean, it gives you a great introduction and you meet so many others also starting there and I have been fortunate in having clear weather both times on the Napoleon Route, it is worth it.
St. Jean to Estella is good for a week walk and if, like me, you have to return to Biarritz airport, there is a good bus service from Estella to Biarritz via San Sebatian.
Hope you have a good time
AlanS