There is never an appropriate time to use voting bots for profit because I believe they are designed for advertising your posts, not making a profit. I haven't made any return on my Facebook ads! That said, the goal is to minimize your loss and if you get a small profit then it's all good. Just monitor the number of bids during the day, and see when there are less people who bids. I found the morning is best for me in my time zone. Thank you for your comment and question @amanze-trillion.