One of the most reassuring things to know about brake noise is that the kind which clears within the first few stops is almost always harmless. If your brakes chirp, scrape, or lightly grind at first and then go quiet, here is what is happening.
Overnight and wet-weather rust
Bare cast-iron rotors flash-rust from overnight dampness or rain - see why rotors rust overnight. The first few brake applications scrub that thin rust film off the rotor, which makes a scrape or light grind that disappears once the surface is clean. This is completely normal.
After the car sits or a wash
The same thing happens after the car sits for a while - see brake noise after sitting - or right after a car wash soaks the brakes; see brakes squeak in the rain. A few stops dry and clean the rotors and the noise clears. Cold, stiff pads can chirp briefly too.
The rule of thumb
Noise that appears cold or wet and vanishes within the first minute of driving is benign - it is surface rust and moisture, not worn parts. This is true even on newer cars with good pads. If it clears with warmth and use, you can relax.
When it is NOT harmless
Be concerned only if the noise persists after the brakes are warm and dry, grows louder over time, or you feel grinding through the pedal - that points to worn pads; see why brakes grind. Persistent noise means inspect and fit fresh pads and hardware.