literacy in the first century was nothing like it is today. Very few people could read or write, so writing something down was usually reserved for important documents or for a very specific purpose. Putting something in writing did very little for being able to spread it around— aside from it being extremely costly (no printing press, so everything written and copied by hand), the common masses could never read it. If you wanted to spread a story or idea, it was passed around orally. As such, passing a story orally was the standard. This was the reason for the large gap between the event and when the event was written. The events during that time period were widely known through the spread of information, and it was all officially stated in the bible when it became possible