I'm sure there were scientists etc that knew that there were different timezones but would the common man know this before telephones etc??? Think on it.
Modern time zones weren't really developed until railway travel became commonplace. They needed a way to regulate arrivals and departures. Before that everyone used solar time, making it noon when the sun cast a shadow directly north or south. I'm sure people figured out the difference between the various regions on Earth as soon as some scientist sat down long enough to do the math.
to add to that, i'm sure that by experience through travel people also figured out that time was different around the world.
I think most anyone who traveled more than 50 miles outside where they were born and raised would know about the difference in time in different zones as most places ran off of solar time. It's like one of those things that people knew but never really placed, if that makes sense? Just like time, time zones are one of those things that man but a name and number on to keep better track of their lives. Edit: Appears it takes me 6+ minutes to talk about time.. lol