Simpler yet would be to do the job scheduling on the PC and have it run an application that writes a command to the Arduino's serial port when it is time to do the LED flashing thing, and have your sketch flash whenever it's told to.
Simpler yet would be to do the job scheduling on the PC and have it run an application that writes a command to the Arduino's serial port when it is time to do the LED flashing thing, and have your sketch flash whenever it's told to.