I went to Mass at the Cathedral about three times, at different times of day and on different days, during the end of my Camino. I was surprised, and delighted, to find that the butafumeiro was swung at all three Masses.
At any rate, my purpose for going to the Cathedral was not to see the (admittedly famous) swinging of the incense, but to give thanks for all the lessons of the Camino, to pray for the safe return home of all the members of my new Camino family, and to ask for blessings for my family and friends who supported me, long distance, every step of the way.
In other words, serendipity may allow one to see the butofumeiro anyway!
Kathy
PS - I notice the original poster has, hopefully, long since finished his/her Camino and is at home, no doubt wistfully toying with the butofumeiro keychain he/she picked up in Santiago, already planning the next visit.