Yes of course you can enter through the International Gateway. You'll have to walk through Canada-Mexico route to get there.
There's a rope up right after France, you can get breakfast pastries there prior to 11, and there's a rope up right past Norway.
So prior to 11 people can walk to the left up to Norway or to the right up to France. All of Norway will be open and the bakery shop in France will be open, everything else will be closed until the world showcase opens