Stevens was in business from 1864-1950. They did not have a "pocket pistol" model, but DID make a "pocket rifle" model from 1869-1916. Am aware of no specific production data based on serial numbers.
@ 1866.
It was made in 1864.
Old catalogs
made about 1918
You will need to start by contacting Mauser
If it is a Colt Vest Pocket model, 1921.
100-300 USD
About 1914. Go to proofhouse.com to look up.
What's the year of my Stevens? Serial number p116495
if it's a 380 caliber then made about 1924
About 92 years old, made in 1917.
The lower the serial number the younger the pistol is