[Ziaholic]

I'd use a state-machine sort of case structure, with a shift register.

When the button is initially pressed, you enter into the START state and read the current time, add your offset time and write it into the shift register. You'd also write the next state into the shift register ... named something like "WAITING".

In the WAITING state, you'd check the current time and the stored time in the shift register. If the current time is still less than the stored time, stay in the WAITING state. Once the current time is greater than the stored time, you exit the WAITING state.

There is a good example of State Machines and shift registers at the LabView Mastery website.