There is a post from Wise Pilgrim today (18/09/17) stating that the Botafumeiro will not be used until further notice due to renovations finally getting around to THAT area of the Cathedral. My assessment is that they waited until after the peak pilgrim season to schedule the necessary work.
I also assess that they will want to get that functionality back up and running ASAP. This is especially the case as there are major Catholic holidays coming up in December and January.
Normally, the botafumeiro is only "flown" for free on the schedule that was presented above. At other times, groups must "subscribe" or pay to have the botafumeiro used. But, as Wise Pilgrim also states, this necessarily means the renovations are almost done. I agree with this assessment. I would have done the same thing, as the botafumeiro is a major tourist draw.
What most people do not know is that the "tiraboleiros" who pull the ropes and provide for the care of the botafumeiro are lay persons (not clergy or seminarians) who must be paid to do this work. It is considered a very high honor to be among the small group of tiraboleiros. The appointment to serve as a tiraboleiro is usually passed down from father to son. So, there men must have jobs nearby that permit them to drop everything to attend to the botafumeiro, then return to their jobs. Coincidentally, several of the current tiraboleiros work at the Pilgrim Office.
The current botafumeiro in use dates from 1855, and was reconditioned in 2006.
Each time it is used, it must be cleaned and prepared for the next use.
In 2017, I understood the subscription cost was about €400 to schedule the botafumeiro. Generally, groups, like the Boy Scouts, police, military, social societies, religious societies from varying parishes, or even tour firms will pay to ensure the botafumeiro would be used when members of that group were in attendance.
Thus, the best time to see the botafumeiro, outside the specified list of dates and occasions mentioned above, is during July and August. This is when the number of groups peaks. At other times of the years, it is a hit and miss proposition.
You can read more about this and everything else relating to the Botafumeiro here:
https://en.wikipedia.org/wiki/Botafumeiro
I hope this helps.