Niantic are hard at it once more and are expanding the Nearby Feature.
According to a new post update, they are expanding the Nearby Feature so that it works all over the United States and in various parts of Europe as well:
We will be expanding the Nearby Pokémon feature to the rest of the continental United States and large parts of Europe. We will continue to review the feedback submitted on our official social media accounts and in other channels and make changes if necessary.”
For anyone in Europe, it could be a couple of hours before you notice anything, but that doesn’t mean stop checking. You might get lucky and the Nearby Feature does come to your exact location, but it might take a few hours, or even a couple of days.