I'm sure there are many factors that play into someone becoming a highly regarded historical figure, such as: whether they are alive or not, how revolutionary the impact was that they left on society, and how many people were affected by the impact the person brought into society. But to be regarded as a historical figure, however, how long (or short) could that take? Mark Zuckerberg introducing Facebook to the world is something that is definitely revolutionary, but would his additions to society even give him the title of a historical figure?
To be honest there there is no such thing as a historical figure really. Well, that would depend on what an historian thinks which can greatly vary from one country to another because of the historiography style used.
Or, we can say that everyone is a historical figure or is to become one at some point which is definitely not when one dies. Any historian working on the French 5th Republic has to study the presidency of Valéry Giscard d'Estaing and he is still alive, or the " revolutionary period " when Robert Badinter worked to abolish the death penalty in France. I studied Mark Zuckerberg in class when we discussed the social and cultural changes from the post-war period until today. That pretty much makes him a historical figure don't you think ? When a 1930s historian worked on WWI, he had to study the Kronprinz and Winston Churchill, yet they were still alive.
So can we say that a person is a historical figure from the moment he dies ? No not really. As soon as he does something of note ? Or maybe as soon as an historian decides to work on this person ? Pretty hard to say. Right next to me I have the photocopy of a text saying that a man named Jean de Chambéry was arrested after poisoning wells in 1348, he says Jews gave him the poison. Is he a historical figure ? Honestly he was more or less a nobody then and no one cares about him today. The only thing he did was commit a crime, and he was not really good at it since he was caught. However this is a great insight for historians who study the Black Death and its consequences on people's minds and the repercussions it had on the Jewish communities living in France.
When Emmanuel Le Roy Ladurie wrote his " revolutionary " book on the history of the French peasants, he researched many people who never did anything revolutionary, never lived their small village, and if we know their name today us only because they were born, married, had kids and then died. Yet Le Roy Ladurie researched them, published a bit of their own history. But you and I will never know the names of these people unless we read the book. However, aren't they historical figures ? You see, this is a very complicated question you ask and I am not sure there is an answer.At best it depends on how historical works is defined in an area of research or in a country ( because we cannot deny that history is not studied the same depending on which country you are, I can see this everyday in this subreddit. And this is not a negative point at all ! ).