Well, it seems like you may still have time to have it serviced now, and it would be ready for Christmas morning....find a reputable repair center in your area, or perhaps someone on the forum could recommend one that ps close to your location. Maybe one of the sponsors???....
it’s a tough question to answer, due to the fact none of us have a clue about how or where it was stored....dramatic changes in temperatures, humidity, and time, can greatly affect petroleum products. So I’d have to say have it looked at before you run it, I understand your plight, in not wanting to see it before Christmas, so just have the service center check it all over, lube it up and give her a whirl....then box it back up, this way your Christmas morning isn’t a static display............Pat
