REV B
A good mechanic can do the front in about an hour.

Gin
Hi Sally, If you are having a shop do the work and they are honest in what they do it should be ready in a matter of an hour or two from when the put it on the lift.

LEXUSRY
IF IT JUST REPLACING BRAKE PADS AND RESURFACING BRAKE ROTORS, LUBRICATE BRAKE CALIPER SLIDING PINS AND BRAKE PAD ENDS. CLEAN BRAKE CALIPERS,SHIELDS ,AND BRAKE PAD SUPPORT BRACKETS, CHANGE BRAKE FLUIDS IF IT IS BLACK OR DIRTY. IT TAKES 2 HOURS FOR THE FRONT AND 2 HOURS FOR THE REAR. IF YOU HAVE TO REPLACE BRAKE CALIPERS, IT TAKES ANOTHER HALF HOUR FOR EACH CALIPER( TOTAL 4 ). REPLACE BRAKE MASTERCYLINDER TAKES ANOTHER HOUR. IF THEY TELL YOU DIFFERENT STORY, THEY ARE HIDING THEIR MISTAKES OR BROKE SOMETHING TO YOUR CAR