I am assuming you would be withdrawing the money for college, yes?
From PIT Bulletin 2006-04:
Q-6. Is there any time limit that the funds deposited into a 529 Plan account must remain in that account prior to withdrawal to qualify for the Pennsylvania State Income Tax deduction?
A-6. There is no time limit that the funds deposited into a 529 Plan account must remain in that account prior to withdrawal to qualify for the deduction. However, donors should verify whether the program restricts early withdrawals.
Joe