Is it time for me to consider Unit Testing?

as I am trying to cater to different cases, I realized that I was modifying the code to consider each different cases, and the code gets more messy...

is it time for me to consider using Unit Testing? any Unit Testing experts there can give me valuable advice?

basically, I have inputs of different timestamps which can start any day any time, and ends any day and time. My required output is a text file which counts the number of inputs and put them into their appropriate time slots, and records the counts from there...

see attached zip file for the inputs and outputs and code..

thanks.