C172 pilot reported a runway incursion when entering the active runway prior to aircraft that just landed exiting the active runway. Pilot had to extend time on runway for aircraft to clear causing a plane on final approach to execute a go around.

Narrative

We were on taxiway 1; lining up to takeoff on RwyXX. A plane landed on runway XX; and taxied down the runway. We began taxing from the hold short line on Taxiway 1; to runway XX. When we turned right and began lining up with centerline we realized the plane had not taxid off the runway yet. To us; they looked like they had passed runway XY/XZ but I do not know for sure.Once we realized they had not taxied off the active runway yet. We stopped. We waited for them to finish their taxi to the end of the runway until they had exited right onto the taxiway. Once they had cleared the active runway we released the brakes and applied full throttle. During this time; there was a plane that was midfield downwind. We had them in sight prior to our taxi onto the runway. By the time that plane was on final; we were still stopped with brakes on; on the runway. That plane had to execute a go around.expectation bias on our part; assuming the aircraft on the runway had turned onto the taxiway.slow taxi of the plane off the runway. Many planes operating in the airport environment (there were at least 5 planes lined up to take off; along with us; the plane on the runway; and 3 planes in the pattern)Applied brakes and waited for plane to exit from the taxiway.Communicated clearly to all planes in the airport environment that we were stopped on the runway.Communcation with the plane performing a go around.