If your flight is considered delayed depends on the time of the arrival at the final destination and not according to the time of the departure. The arrival time is counted as the time when the aircraft reaches the final destination and at least one of the aircrafts doors opens and the passengers are permitted to disembark.
Flight delay compensations are based on the distance of the flight and the duration of the delay. This is what you are entitled to:
A claim for compensation for a delayed flight could be argued if your flight arrives at the final destination with a delay of more than 3 hours in comparison to scheduled time of arrival. The distance is estimated on basis of the last destination where denied boarding or a cancelled flight leads to a delayed arrival in relation to the original timetable.
Air passenger rights also applies if your flight arrives at the final destination with a delay of more than 3 hours due to a missed connecting flight. In order to be entitled to compensation, all flights must have the same reservation number and not been purchased separately.
If the delay could have been prevented and it thus can be considered to be within the operating air carriers control, a compensation claim could be argued. Otherwise, the operating air carrier themselves must prove that the delay was due to an extraordinary circumstance. Mostly, they refer to the delay as "technical problems" or other operational circumstances. However, most court cases have stated that this type of circumstances is not sufficiently extraordinary to annul the obligations to the air passengers.