When you do the replacement, make sure you use plenty of brake grease to prevent any pad knocking. Mine were quite loud and I had to redo to the pads to add more Cerami-Glyde. Though that may be related to my use of Akebono Euro pads instead of OEM.

 

So any videos or instructions on replacing the pads and sensors?

 

Rolex,
Apologies if I sounded a bit critical. Didn't mean to be. Obviously, you have it well in hand with your inspections. I'm learning that I also should be planning ahead for tires and brakes!
To attempt to say something more useful to your original question, I just replaced the rear pads in my '04 C2. I'll guess that it was 1000 miles between the first warning light and the replacement. (I drive the car 350 miles a week.) The pads still had material, but one of the warning sensors was half worn through at that point. Bottom line, I'm surprised at how fast the rears wear. I have about 30k on it since everything was new (when I bought the car 20 months ago) and the fronts are at ~ 50% ish, and the rears were gone. Just like the tires, come to think of it. Welcome to rear weight bias I guess. I drive at a "brisk" street pace, nothing crazy and no track time.

 

I'm with D.L. on changing rotors. I get at least two sets of pads out of one rotor. You can buy a cheap micrometer off the internet for $15. The fancy ones built especially for rotors are $40. I've got 35K on an 09 Boxster with 15 track days with the original OEM rotor on the rear. I ordered a new rotor and pads all around, but when I measured the rear it was no where near the minimum. The front is a different story. Put on a dedicated track rotor late 2017 and replaced last August. The brake pad dampers on the front are a pain. Took them out when we put on the track rotor. Saved the original OEM rotors and pads. Put the OEM pads back in if I'm going any extensive street driving since the track pads really squeak. Changing pads is now a simple job front and rear. I have new sensors but have been reusing the fronts. The rears practically feel apart when we took them off. Assume from engine and exhaust heat. Wire tied the rear ones out of the way but reinstalled the fronts. Many if not most who regularly track their cars have the brake pad sensors tied out of the way or on a shorted plug. Makes changing pads quicker. Pads and rotors are checked after almost every session but thoroughly each morning. You can't completely remove the sensors or you get an open circuit and a brake pad warning light. Get replacements for the two rotor retaining screws. They take a beating if you use an impact driver. If you are just beginning Harbor Freight sells an inexpensive low profile aluminum jack by Pittsburgh which is great for jacking up the car. Get a (hockey) puck to protect jacking points. The price from a dealer or even an indy to this work is all the motivation I've ever needed.

09 Boxster PDK w/Sport/Sport+
00 BMW 320Ci-Gone and missed
85 Saab 900T autobahn cruiser for 5 years
65 Mustang 289 4 speed First love​​​​​​
16 MB GLC 300 DD