In this early period, the serial number can be found on the bridge of the instrument (see image).Here are the rough serial number ranges for the early Esquires and Telecasters: By mid-1954, Fender began using a universal serial number sequence for all its instruments.These are generally referred to as F series due the large Fender branded F on the neckplates of the era.This period also saw a switch from the orginal four-bolt neckplate of the '60s to a three-bolt neckplate in just one example of cost-saving costs introduced under CBS.Perhaps the best place to start when dating your Fender is to get an approximate idea of the era based on the instrument's design and components.This can be a tall order for someone less versed in guitar history, but we do have some resources here on Reverb to help you out.At this time, the location of the serial number also shifted from the bridge to the neckplate (the metal plate located on back of where the neck meets the body).
I will also mention briefly pot-codes as a resource (numbers on the internal potentiometers of the guitar).
Similarly, take a look at Behold the Jazzmaster for general timeline of the history of everyone's favorite offset guitar.
For Fender during the turning point era of the mid-'60s, check out Fender and the CBS Takeover.
Through much of Fender's production history, Fender workers would print or write a production date on both bodies and necks where the two pieces meet.
These dates will tell when the original part was manufactured, but are not exact indicators of when the guitar was actually put together and finished.