A quick answer, Follow/Unfollow action time is calculated automatically based on your account status.

Here is why:

Due to recent Instagram updates, accounts get easily banned from sending requests. We have somehow figured out the most efficient way to decrease the chance of this by randomizing requests in our way. 
No matter what tool you use or even do it manually you can roughly send more than 200 follow requests per day and the threshold gets lower every time you get temporary action blocked.

We should ask you to just trust us and consider the app on Auto-Pilote sending requests and check out the results in wider time frames. 

The time we could send thousands of requests per day on Instagram has passed and we should be more patient and look at the process in wider time frames.