how long do I have before replaceing brakes

My little brake idiot light just started coming on. It is mostly a light flicker when coming to a stop, and a bright steady light when I really press on the pedel hard while stopped at a light.

Do I have time to get some mail order pads and rotors through the internet . . . or should I get them replaced today?

I realize that the pads should be replaced right away, but how much time does one usually have after the light starts coming on before it gets to a critical point? Enough time to get the parts throught the mail?

Just got the car out of the shop (Mr. MB Motors) to replace the flex disk and Enrique didn't say anything about the brakes.

(Subject car is an '89 W124 coupe.)

As always, thanks to everybody for sharing their wisdom.

[Jackd]

The light comes on way before damage is done to the brake rotors. You would not hurt anything if you waited a few days before doing the job (unless you drive 1000 mi per day in traffic)