This is a hotly debated topic: captive orthodoxy vs. Natural hydration. There are not easy answers here. Orthodoxy has is to hydrate when they’re awake, ‘cause that’s when they drink. Natural hydration says humidity nearing 100% at night is more in keeping with the natural humidity cycle, and the chams loose less moisture to respiration during the night, so their drinking requirements during the day are diminished. The idea is to mist before lights on to create a nice dew-like mist on the leaves for morning drinking, little to no misting during lights on, and misting just after lights out, with fogging starting at 3 or 4 am and ending before lights on. The idea is high humidity at night, drinkable dew in the morning, humidity drop during the day, and humidity rise at night.
don’t get me wrong. A multitude of chams have been raised and bred using several daytime misting/fogging sessions, and nothing at night. So both strategies work. It’s up to you to look further into this.
ps: I’ve been keeping chams for less than 2 years, and am just regurgitating what I’ve read and heard.