Thank your feature (about the night dm cvar) works fine, but sometimes start a vote while 10 minutes of the map have been passed and change the map after another 10 minutes, as it should be, but quite strange the vote show up 10 minutes before it have to. I should mention that in half of the times works normally and vote start when it supposed to start.
P.S I use version prior this 2017-05-23 | v5.7.0-878