Hello!
Great question; I would say it depends from person to person. For a big race like that and then a ski trip on top of it, I would give yourself at least four days super easy. That might also need to be a week too. Start back training easy and see how that goes! Listen to your body (sounds like you are doing that); when you start getting good energy back, and your legs aren’t tired going up a flight of stairs, you are probably ready to get back to training.
As for a ski instructor! It depends where you Nordic ski; it sounds like you are in the Methow Valley for Ski to the Sun Ski Marathon. I can give you some recommendations if that is the area you are looking in. Shoot me an email if so!
Maya