I don't have the same brakes, but ...
I asked the same question a cpl years ago but never really got a definitive answer, other than don't wait to hear scraping metal sounds
I've changed mine twice since then. neither time did they look excessively worn
for me, I'll do it if the brake is making noise or there's a noticeable loss of performance, like from some kind of contamination - even after checking wheel alignment & cleaning the rotor
it was interesting to see that the inner & outer pads wear differently
old vs new
honestly don't remember what exactly these pics are that I took
