If your electric company offers lower rates for consuming electricity off hours, then that’s your answer. Otherwise, it doesn’t matter much.
My pool seems far more likely to get used in the later part of the day, so I run it during the day because I want it skimmed for my swimmers. But, I don’t save money running it at night.
Personally, I enjoy being in the pool when it is circulating. For others, it doesn’t matter.