Not all anti freeze is poisonous so it depends on the maker of the anti freeze and what type of antifreeze it is...www.bcspca.com
How Long Does A Dog Live After Drinking Antifreeze?
It Depends on how much he has consumed but usually just a few hours max.
Not very long at all without prompt treatment. If you think your dog has gotten into something like that they need to see the closest vet immediately.