Stamford has a City Directory where the first issue was in 1872. I doubt
that Greenwich had one that early. My guess is that their first one was around
1900. You can call the Greenwich Public Library or the Greenwich Historical
Society (Bush-Holly House) for more information. I believe that both places
have the Greenwich City Directories. Nearby Port Chester NY also has City
Directories in their Public Library.
Hope this is helpful to you.