While it can be very inspiring and emotional for many pilgrims to actually see the Botafumeiro 'fly' in person, you can always go to You Tube at any time, and query 'Botafumeiro' to obtain a multitude of videos taken by many tourists and pilgrims. The view, ceremony and hymn are always the same...only the congregation varies...
As stated above, other than the liturgical schedule posed by the Cathedral on its web site, and also on the Pilgrim Office website, the Botafumeiro is used only when a group subsidizes its' use. Thus, to know when it will be used, it is helpful to PAY ATTENTION to what is occurring in and around Santiago. For example:
- If there are many tour groups on a given morning (identify them by the various signs, flags and umbrellas used), it is likely someone has funded the Botafumeiro. For example, if you have eight groups of 50 each from a cruise ship docked at Vigo, you do not want to disappoint, do you?
- If there are large groups of pilgrims arriving in Plaza Obradoiro (you can tell them by their identical t-shirts or uniforms), it is likely the Botafumeiro has been arranged. Once schools are out, large groups of scouts and students converge on the Camino...etc.
- If the area in front of the Parador is lined with similar or identical expensive limousines, it is a sign that some VIP is staying there, with an entourage, and it is very possible they have arranged for the Botafumeiro. Meetings at the Parador are 'hip' with the Spanish and Galician governments.
- If the Spanish military is present in what appears to be unit-sized groups (usually 100 or more) it is likely that a ceremony is occurring in conjunction with the noon Pilgrim Mass. They will have arranged for the Botafumeiro to be used. The spring season (May - June) is popular for a variety of ceremonies.
Remember, Santiago (Saint James) is the patron saint of ALL of Spain (and Portugal too), at least for Catholics. So, this explains why Santiago is popular throughout all of Spain.
As an aside: Most Christian nations (and even many predominately non-Christian places) have a patron saint, e.g. Ireland - St. Patrick, US - The Virgin Mary, and so forth... Spain attributes its victories of the occupying Moors to the intercession of Santiago. Hence, he has had pride of place for more than 500 years, or as long as there has been a national called Spain. Even the UK countries of England (St. George), Scotland (St. Andrew), and Wales (St. David) have their original Christian patron saints.
For more information on this, check out this accounting:
https://en.wikipedia.org/wiki/Patron_saints_of_places
NOTE - back on track: They (military formations) will also sit in the center, front-most pews nearest the main altar. This consumes a lot of valuable seating and makes the remainder of the Cathedral artificially crowded.
ARRIVE EARLY to get a seat. Security limits entry the maximum number permitted by the local fire marshal. If you arrive after 11:15 for the noon Mass during the summer, you may not get in.
Rucksacks and daypacks are NOT permitted for security reasons. Leave your bag somewhere safe, or put it into a consignment location at: Pilgrim House (rua Nova 19), the Pilgrim Office, Campo-Stellae (shop at top of Plaza da Praterias stairs to the right), and others around the old town. All places charge the same €2 for the entire day. Make sure you know how late you can recover your bag, so you are not locked out in the evening.
The best views are ALWAYS in either the South or North transepts, as this is the axis of swing for the Botafumeiro. If you side in the main part of the Cathedral (East-West axis) you only see the small portion of the swinging censer. For reference, the Cathedral entrance is via the South transept and the exit is via the North transept, at least until the renovation work is more complete.
Hope this all helps.