When you use anti-fog products on your inside glass they can be **** to get off the glass, should it not work out for you.
I was with a friend on a trip, we were in Colorado going to ascend Pikes Peak, it was a miserable day, he used some sort of anti-fog on the windshield.
First thing was it didn't do anything to help reduce fogging, it made a mess out of the glass that didn't want to come off, when you tried to clean the glass the stuff just smeared.
At night when oncoming cars approached the windshield looked like it was never cleaned.
Learn to work your HVAC, then as soon as you start to see fogging you will know exactly how to stop it.