As mentioned above your brakes will feel "good" up until you have damaged them by running out pad material or have hit wear indicators (when applicable).
BMW and many mechanics tell you when they are low well in advance out of safety. (Knowing that most people wait for a problem to arise and it could be too late).
As per the service manual there are levels of thickness on the pad materiel before they need replacement. You are welcome to check your personal vehicle and the listing in the service manual and judge for yourself if it is time. (It's not hard at all). Or get a second opinion from a reputable shop.
You should not wait for a problem to find you when it comes to brakes. They are arguably the most important thing next to tires on your car.