@atbrygge yes (not a lot know this) but 'god jul' you say before, and 'glædelig jul' is during. (May you have a.. vs enjoy this time) but since a lot don't know this it gets more and more mixed up, and nobody really cares (that's a good thing here)
@boab@atbrygge I agree: you can say "god jul" to friends and colleagues (or whomever you may please) the last time you see them before Christmas - not "Glædelig" which is more like "now it's Christmas" or "welcome to Christmas, everybody", which usually means the ones you actually celebrate Christmas with... Or people you meet on Christmas day (or, as we're in Denmark: the day before, as Danes tend to celebrate things the day before they actually take place ...)