I echo what a few have mentioned about being flexible. No harm in planning at all, but it's also good to hold it lightly.
A few random thoughts:
The alternate way between Leon and Astorga is lovely, the highway not so much. I would be thinking Leon-Vilar de Mazarife-Vilares de Orbigo-Astorga-Rabinal-Acebo etc...
Amen to what people have said about Samos.
After Sarria, it pays to stay between popular stage-ending towns. So you can avoid Sarria and stay in Barbadelo, or stay in Leboreiro instead of Melide. You'll be spared the crowds.
It's not that bad, really. I stayed there after taking a fall, and to avoid hypothermia on a wet and frigid late winter/early spring day. The welcome was warm and the hospitality had heart.
One option you might consider if you have the time is to walk the detour to
Yuso/Suso. There is lodging at the Hosteria San Millan, at Yuso. NOT cheap. In fact, definiely a splurge. But 2 Irish pilgrims I met were very glad they did this detour and stayed there (it's in
Brierley, I think). The best part is that they saw Cirueña without going through the golf course.