B747 Check Pilot reported a hard landing during a qualification check with a new First Officer.

Narrative

Conducting a release to line check for transition FO. Good weather but windy with winds on ATIS of 240/11G19 and 250/17 reported by tower. Aircraft was light at 476k and we elected to do a flaps 25 landing. This was my first leg with the student so we thoroughly briefed the arrival (ZZZZZ); approach; landing and threats. From his training record and flying up to that point in the flight he was doing well. I would rather over brief on my one look with a student. We even talked through every aspect of the landing including power pull and concluded with DO NOT PULL YOUR POWER EARLY as the aircraft can be unforgiving lightweight with a big gusty headwind (even though tower later removed the gust to a steady state wind). He did great on the arrival and approach despite being held high due to inbound traffic landing at ZZZ. He flew the approach well despite the warm afternoon winds. He landed on centerline but slightly flat (telemetry reported 2.2 degrees). I gave him a direct; concise FLARE command just prior to hitting the runway. It was too late as he had pulled the power and we hit the runway hard (telemetry 1.98g). We reported the landing to maintenance and wrote it up in the logbook as a possible hard landing; later confirmed. Suggestion for improvement: I've replayed this hundreds of times in my head. Your always on the razors edge on a release. You've seen the grades; and a small snippet of their flying skills with the takeoff. I tend to over brief the arrival/landing phase asking them what they're looking for; hearing; seeing; thinking about during each step of the process. It gives me a better sense of where their mind is. It allows me to provide a little more instruction without making them feel like its an entirely different perspective. I want them to be comfortable; confident; and positive; not second guessing previous instruction. We finished with; Do not pull the power early and talked about how its more forgiving if you leave it in too long than pull it early. I gave that advice again as we lined up on final waiting to intercept glideslope; DO NOT PULL YOUR POWER EARLY We talked about it at length at altitude and the one last direct time as we started the approach but you're still on that edge as you land. When do you interject verbally? When do you take the aircraft? I chose the verbal interface because everything else was on point but I was a heartbeat late and we landed hard. I could have taken the aircraft but I think that would have been premature based on the way he was flying. I fully believe the process was correct but the outcome was poor. It will be with me every landing going forward.