I didn't get an endoscopy through my nose, but I got one through my esophagus and a portion of my upper intestines once.
Do you know if they're going to sedate you/put you under anesthesia at all? They did that to me for the procedure, but I was also younger than I am now and doctors seem to sedate kids for a lot of things they don't do that to adults for.
If they're sedating you though that'll be good, because depending on how they do so you might not remember the procedure at all.