You don't need to wait overnight. Conditioner works instantly and at that level I would be doing a water change ASAP. Anything over 0ppm is harmful and at 1ppm which is what it looks like from your picture it is definitely going to be causing irritation to his gills etc.
I would do a 100% water change as otherwise there will still be ammonia present in your aquarium.
I would also test for ammonia coming out of the tap. It is not uncommon for there to be ammonia present in some tap water.