I like, too, to walk without a set schedule. But the experience (a couple of times, in early October) of looking for a bed, very tired, and receiving two or three times the "sorry, we are completo" answer was not exactly pleasant.
I suggest:
Make a sketchy plan of your daily journey. Avoid "standard" stops (Portomarín, Palas de Rei, Arzúa, Pedrouzo), where everybody is looking for a bed. Prefer little villages.
In the morning, think again about the distances, how your body feels, the weather, decide and phone to make a reservation. This will give you both some flexibility and peace of mind.
If you are still in the Camino around 4 PM, call again to confirm your arrival. Sadly, many walkers change their mind but not notify the albergues; owners know that and tend to give the available beds after some time.