Alarm Clock Project

Hi

I have been following an online tutorial in order to prototype an alarm clock and have successfully done so using a Sparkfun RTC Module 1307 and a Sainsmart LCD Keypad Shield for an Arduino Uno. The project link is stated below:

https://codebender.cc/sketch:27095#AlarmClock%20Example.ino

I would like to extend the functionality of this by switching on an LED 15 minutes before the scheduled alarm time. Would anyone be able to advise me with how this should be coded? I am new to using Arduino and have tried to do this

Thanks

I am new to using Arduino and have tried to do this

Please post the code you tried and explain what it did/did not do.

When posting the code please select it and use code tags by clicking on the </> icon top/left of the forum editor window. Using these tags makes it easier to copy the code into an editor to provide advice and help.