I only mist when the lights are out. With that being said, I believe there are at least some on here, who mist 30 mins BEFORE lights go off, instead of 30 minutes AFTER lights go off. I'll share my lights/mist/fog schedule with you, but please keep in mind I live in the US, and my cage is all open screen. It doesn't take much to get high humidity for me. Everyone's situation is different, and your goal is to keep the humidity in the 40-50% or so range during the day, and 80-100% at night. The reason I could see to mis 30 minutes BEFORE lights off at night, would be to give your chameleon a supplement of water to drink before they go to sleep.
I personally have never seen my chameleon need to drink (I have a dripper but he doesn't use it), and his poop+urates has always looked excellent for hydration. But again, high humidity is not an issue for me.
My schedule:
7:00am lights on
7:00pm lights off
7:30pm 2 minute misting session
1:00am 2 minute misting session
1:00am 6am fogger is on entire time
6:30am 2 minute misting session