Breaking lease contract

I have a signed a 9 year lease contract starting middle of July 2014. Tomorrow I will give my landlord notice that I will be moving out in the middle of July.

This means:
1) I will leave the apartment exactly 3 years after moving in
2) I will give notice 3 months before my lease contract has reached 3 years

In this case, will I have to pay the penalty of 1 months rent?
Is the penalty decided on the date you give notice or the date you actually move out and stop paying?

Thank you!