Hello

My 2008 x5 recently displays the brake wear sensor light and the front brake in the service info says 9000km and the rear brake says 27000 km

Can I wait until I change the front brake pad to change the sensor?
In the meantime, can I rely on the squeaking sound to tell me to change the brake pad? Also, do I have to change the rotor when I change the pad?

My last question is how many km approximately can I drive when the brake wear sensor light is on?

Thanks
Henry