What could it mean to have a negative time?

A negative time could possibly mean in the past ... or in other words, already happened.

Time is negative "time" is a method founded by man to record events ... So to conclude this question, you can give negative time as in countdowns, or past events. But there is no such thing as a negative in a chronological time graph, that starts and ends with positive numbers, unless you consider BC as the negative on the line chart