Basically this is a question of how far and how much information spread throughout Europe during the middle ages. How long did it take for news of a death of notably bit of royalty in Russia to reach Western Europe, such as the court of the King of Portugal, or vice versa?
At least a couple on moths. News used to travel just like men did, so by foot, horse and and boat. Unless the news was very important (in that case you’d have a bunch of horsemen riding all over Europe bringing the news) mainly the merchants used to spread the news all over Europe, and for an obvious reason they were quite slow