I go to following usgs site and check the gauge height. It is updated every hour. If you see a spike in level, you know they turned it on and its running. That being said, they can and do stray from the schedule. Best thing to do is call to see when they are planning to generate and check the gauge for a spike confirming it. If the gauge history shows regularity or that they have been running for consecutive days, there's a good chance of them sticking to that pattern ish. It still comes down to, they turn it on when they decide to.
https://waterdata.usgs.gov/mo/nwis/uv/?site_no=06922500&PARAmeter_cd=00065,00060