Hello, it’s better if you try with for 30 and 15 minutes to see how much the humidity will raise, because it depends on how many frost your humidifier can do, or you can buy a humidity controller from AliExpress and connect to it, I’m doing that, you define how much rh you want and when it’s get to the value it turns off, then when it gets to a lower value turns on again.
Hope it helps you!