Use of comma following prepositional phrase

Is a comma required after the date (year only or day of week only) that is in a prepositional phrase before the subject of the sentence? For example:

In 1966 I began college.


Solution 1:

You have to ask how strong an interruption to the sentence the prepositional phrase makes. I would say that in that case the answer was not very, and that consequently no comma was needed.