To compare to that time span is the two earliest biographies of Alexander the Great, which were written by Arrian and Plutarch. They weren't written until 400 years after his death in 323 BC. Historians consider these biographies to be trustworthy. Legendary material for Alexander didn't start to appear until centuries after the two biographies were written. The gospels were written 30 years later.
Luke wrote Acts and it ends unfinished. Paul was the central figure and it ends with him under house arrest in Rome, which means it was probably finished before Pail was put to death. This means Acts cannot be dated any later than AD 62. Acts is the second part of a two-part work; the Gospel of Luke was the first part. This means that Luke must have been written earlier than Acts. Also Luke incorporates parts of the Gospel of Mark, which means Mark was written even earlier.